diff --git a/src/core/ddsi/include/dds/ddsi/q_entity.h b/src/core/ddsi/include/dds/ddsi/q_entity.h
index 1d20d34..0acd3da 100644
--- a/src/core/ddsi/include/dds/ddsi/q_entity.h
+++ b/src/core/ddsi/include/dds/ddsi/q_entity.h
@@ -338,6 +338,7 @@ struct proxy_endpoint_common
   struct addrset *as; /* address set to use for communicating with this endpoint */
   nn_guid_t group_guid; /* 0:0:0:0 if not available */
   nn_vendorid_t vendor; /* cached from proxypp->vendor */
+  seqno_t seq; /* sequence number of most recent SEDP message */
 };
 
 struct proxy_writer {
@@ -608,8 +609,8 @@ void purge_proxy_participants (struct q_globals *gv, const nn_locator_t *loc, bo
 
 /* To create a new proxy writer or reader; the proxy participant is
    determined from the GUID and must exist. */
-  int new_proxy_writer (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const struct nn_plist *plist, struct nn_dqueue *dqueue, struct xeventq *evq, nn_wctime_t timestamp);
-int new_proxy_reader (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const struct nn_plist *plist, nn_wctime_t timestamp
+  int new_proxy_writer (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const struct nn_plist *plist, struct nn_dqueue *dqueue, struct xeventq *evq, nn_wctime_t timestamp, seqno_t seq);
+int new_proxy_reader (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const struct nn_plist *plist, nn_wctime_t timestamp, seqno_t seq
 #ifdef DDSI_INCLUDE_SSM
                       , int favours_ssm
 #endif
@@ -623,8 +624,8 @@ int new_proxy_reader (struct q_globals *gv, const struct nn_guid *ppguid, const
 int delete_proxy_writer (struct q_globals *gv, const struct nn_guid *guid, nn_wctime_t timestamp, int isimplicit);
 int delete_proxy_reader (struct q_globals *gv, const struct nn_guid *guid, nn_wctime_t timestamp, int isimplicit);
 
-void update_proxy_reader (struct proxy_reader *prd, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp);
-void update_proxy_writer (struct proxy_writer *pwr, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp);
+void update_proxy_reader (struct proxy_reader *prd, seqno_t seq, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp);
+void update_proxy_writer (struct proxy_writer *pwr, seqno_t seq, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp);
 
 int new_proxy_group (const struct nn_guid *guid, const char *name, const struct dds_qos *xqos, nn_wctime_t timestamp);
 void delete_proxy_group (struct ephash *guid_hash, const struct nn_guid *guid, nn_wctime_t timestamp, int isimplicit);
diff --git a/src/core/ddsi/src/q_ddsi_discovery.c b/src/core/ddsi/src/q_ddsi_discovery.c
index fa08998..227c961 100644
--- a/src/core/ddsi/src/q_ddsi_discovery.c
+++ b/src/core/ddsi/src/q_ddsi_discovery.c
@@ -1120,7 +1120,7 @@ static struct proxy_participant *implicitly_create_proxypp (struct q_globals *gv
   return ephash_lookup_proxy_participant_guid (gv->guid_hash, ppguid);
 }
 
-static void handle_SEDP_alive (const struct receiver_state *rst, nn_plist_t *datap /* note: potentially modifies datap */, const nn_guid_prefix_t *src_guid_prefix, nn_vendorid_t vendorid, nn_wctime_t timestamp)
+static void handle_SEDP_alive (const struct receiver_state *rst, seqno_t seq, nn_plist_t *datap /* note: potentially modifies datap */, const nn_guid_prefix_t *src_guid_prefix, nn_vendorid_t vendorid, nn_wctime_t timestamp)
 {
 #define E(msg, lbl) do { GVLOGDISC (msg); goto lbl; } while (0)
   struct q_globals * const gv = rst->gv;
@@ -1275,7 +1275,7 @@ static void handle_SEDP_alive (const struct receiver_state *rst, nn_plist_t *dat
     {
       if (pwr)
       {
-        update_proxy_writer (pwr, as, xqos, timestamp);
+        update_proxy_writer (pwr, seq, as, xqos, timestamp);
       }
       else
       {
@@ -1287,7 +1287,7 @@ static void handle_SEDP_alive (const struct receiver_state *rst, nn_plist_t *dat
           new_proxy_writer (&ppguid, &datap->endpoint_guid, as, datap, channel->dqueue, channel->evq ? channel->evq : gv->xevents, timestamp);
         }
 #else
-        new_proxy_writer (gv, &ppguid, &datap->endpoint_guid, as, datap, gv->user_dqueue, gv->xevents, timestamp);
+        new_proxy_writer (gv, &ppguid, &datap->endpoint_guid, as, datap, gv->user_dqueue, gv->xevents, timestamp, seq);
 #endif
       }
     }
@@ -1295,14 +1295,14 @@ static void handle_SEDP_alive (const struct receiver_state *rst, nn_plist_t *dat
     {
       if (prd)
       {
-        update_proxy_reader (prd, as, xqos, timestamp);
+        update_proxy_reader (prd, seq, as, xqos, timestamp);
       }
       else
       {
 #ifdef DDSI_INCLUDE_SSM
-        new_proxy_reader (gv, &ppguid, &datap->endpoint_guid, as, datap, timestamp, ssm);
+        new_proxy_reader (gv, &ppguid, &datap->endpoint_guid, as, datap, timestamp, seq, ssm);
 #else
-        new_proxy_reader (gv, &ppguid, &datap->endpoint_guid, as, datap, timestamp);
+        new_proxy_reader (gv, &ppguid, &datap->endpoint_guid, as, datap, timestamp, seq);
 #endif
       }
     }
@@ -1337,7 +1337,7 @@ static void handle_SEDP_dead (const struct receiver_state *rst, nn_plist_t *data
   GVLOGDISC (" %s\n", (res < 0) ? " unknown" : " delete");
 }
 
-static void handle_SEDP (const struct receiver_state *rst, nn_wctime_t timestamp, unsigned statusinfo, const void *vdata, uint32_t len)
+static void handle_SEDP (const struct receiver_state *rst, seqno_t seq, nn_wctime_t timestamp, unsigned statusinfo, const void *vdata, uint32_t len)
 {
   struct q_globals * const gv = rst->gv;
   const struct CDRHeader *data = vdata; /* built-ins not deserialized (yet) */
@@ -1370,7 +1370,7 @@ static void handle_SEDP (const struct receiver_state *rst, nn_wctime_t timestamp
     switch (statusinfo & (NN_STATUSINFO_DISPOSE | NN_STATUSINFO_UNREGISTER))
     {
       case 0:
-        handle_SEDP_alive (rst, &decoded_data, &rst->src_guid_prefix, rst->vendor, timestamp);
+        handle_SEDP_alive (rst, seq, &decoded_data, &rst->src_guid_prefix, rst->vendor, timestamp);
         break;
 
       case NN_STATUSINFO_DISPOSE:
@@ -1736,7 +1736,7 @@ int builtins_dqueue_handler (const struct nn_rsample_info *sampleinfo, const str
       break;
     case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER:
     case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER:
-      handle_SEDP (sampleinfo->rst, timestamp, statusinfo, datap, datasz);
+      handle_SEDP (sampleinfo->rst, sampleinfo->seq, timestamp, statusinfo, datap, datasz);
       break;
     case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_WRITER:
       handle_PMD (sampleinfo->rst, timestamp, statusinfo, datap, datasz);
diff --git a/src/core/ddsi/src/q_entity.c b/src/core/ddsi/src/q_entity.c
index 42ccf84..da19224 100644
--- a/src/core/ddsi/src/q_entity.c
+++ b/src/core/ddsi/src/q_entity.c
@@ -3659,15 +3659,15 @@ void new_proxy_participant
         assert (is_builtin_entityid (guid1.entityid, proxypp->vendor));
         if (is_writer_entityid (guid1.entityid))
         {
-          new_proxy_writer (gv, ppguid, &guid1, proxypp->as_meta, &plist_wr, gv->builtins_dqueue, gv->xevents, timestamp);
+          new_proxy_writer (gv, ppguid, &guid1, proxypp->as_meta, &plist_wr, gv->builtins_dqueue, gv->xevents, timestamp, 0);
         }
         else
         {
 #ifdef DDSI_INCLUDE_SSM
           const int ssm = addrset_contains_ssm (gv, proxypp->as_meta);
-          new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp, ssm);
+          new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp, 0, ssm);
 #else
-          new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp);
+          new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp, 0);
 #endif
         }
       }
@@ -3696,7 +3696,7 @@ int update_proxy_participant_plist_locked (struct proxy_participant *proxypp, se
   nn_plist_mergein_missing (new_plist, datap, PP_PRISMTECH_NODE_NAME | PP_PRISMTECH_EXEC_NAME | PP_PRISMTECH_PROCESS_ID | PP_ENTITY_NAME, QP_USER_DATA);
   nn_plist_mergein_missing (new_plist, &proxypp->e.gv->default_plist_pp, ~(uint64_t)0, ~(uint64_t)0);
 
-  if (seq && seq > proxypp->seq)
+  if (seq > proxypp->seq)
     proxypp->seq = seq;
 
   switch (source)
@@ -3953,7 +3953,7 @@ uint64_t get_entity_instance_id (const struct q_globals *gv, const struct nn_gui
 
 /* PROXY-ENDPOINT --------------------------------------------------- */
 
-static void proxy_endpoint_common_init (struct entity_common *e, struct proxy_endpoint_common *c, enum entity_kind kind, const struct nn_guid *guid, nn_wctime_t tcreate, struct proxy_participant *proxypp, struct addrset *as, const nn_plist_t *plist)
+static void proxy_endpoint_common_init (struct entity_common *e, struct proxy_endpoint_common *c, enum entity_kind kind, const struct nn_guid *guid, nn_wctime_t tcreate, seqno_t seq, struct proxy_participant *proxypp, struct addrset *as, const nn_plist_t *plist)
 {
   const char *name;
 
@@ -3968,6 +3968,7 @@ static void proxy_endpoint_common_init (struct entity_common *e, struct proxy_en
   c->as = ref_addrset (as);
   c->topic = NULL; /* set from first matching reader/writer */
   c->vendor = proxypp->vendor;
+  c->seq = seq;
 
   if (plist->present & PP_GROUP_GUID)
     c->group_guid = plist->group_guid;
@@ -3991,7 +3992,7 @@ static void proxy_endpoint_common_fini (struct entity_common *e, struct proxy_en
 
 /* PROXY-WRITER ----------------------------------------------------- */
 
-int new_proxy_writer (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const nn_plist_t *plist, struct nn_dqueue *dqueue, struct xeventq *evq, nn_wctime_t timestamp)
+int new_proxy_writer (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const nn_plist_t *plist, struct nn_dqueue *dqueue, struct xeventq *evq, nn_wctime_t timestamp, seqno_t seq)
 {
   struct proxy_participant *proxypp;
   struct proxy_writer *pwr;
@@ -4008,7 +4009,7 @@ int new_proxy_writer (struct q_globals *gv, const struct nn_guid *ppguid, const
   }
 
   pwr = ddsrt_malloc (sizeof (*pwr));
-  proxy_endpoint_common_init (&pwr->e, &pwr->c, EK_PROXY_WRITER, guid, timestamp, proxypp, as, plist);
+  proxy_endpoint_common_init (&pwr->e, &pwr->c, EK_PROXY_WRITER, guid, timestamp, seq, proxypp, as, plist);
 
   ddsrt_avl_init (&pwr_readers_treedef, &pwr->readers);
   pwr->n_reliable_readers = 0;
@@ -4084,7 +4085,7 @@ int new_proxy_writer (struct q_globals *gv, const struct nn_guid *ppguid, const
   return 0;
 }
 
-void update_proxy_writer (struct proxy_writer *pwr, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp)
+void update_proxy_writer (struct proxy_writer *pwr, seqno_t seq, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp)
 {
   struct reader * rd;
   struct pwr_rd_match * m;
@@ -4093,31 +4094,35 @@ void update_proxy_writer (struct proxy_writer *pwr, struct addrset *as, const st
   /* Update proxy writer endpoints (from SEDP alive) */
 
   ddsrt_mutex_lock (&pwr->e.lock);
-  if (! addrset_eq_onesidederr (pwr->c.as, as))
+  if (seq > pwr->c.seq)
   {
-#ifdef DDSI_INCLUDE_SSM
-    pwr->supports_ssm = (addrset_contains_ssm (pwr->e.gv, as) && pwr->e.gv->config.allowMulticast & AMC_SSM) ? 1 : 0;
-#endif
-    unref_addrset (pwr->c.as);
-    ref_addrset (as);
-    pwr->c.as = as;
-    m = ddsrt_avl_iter_first (&pwr_readers_treedef, &pwr->readers, &iter);
-    while (m)
+    pwr->c.seq = seq;
+    if (! addrset_eq_onesidederr (pwr->c.as, as))
     {
-      rd = ephash_lookup_reader_guid (pwr->e.gv->guid_hash, &m->rd_guid);
-      if (rd)
+#ifdef DDSI_INCLUDE_SSM
+      pwr->supports_ssm = (addrset_contains_ssm (pwr->e.gv, as) && pwr->e.gv->config.allowMulticast & AMC_SSM) ? 1 : 0;
+#endif
+      unref_addrset (pwr->c.as);
+      ref_addrset (as);
+      pwr->c.as = as;
+      m = ddsrt_avl_iter_first (&pwr_readers_treedef, &pwr->readers, &iter);
+      while (m)
       {
-        qxev_pwr_entityid (pwr, &rd->e.guid.prefix);
+        rd = ephash_lookup_reader_guid (pwr->e.gv->guid_hash, &m->rd_guid);
+        if (rd)
+        {
+          qxev_pwr_entityid (pwr, &rd->e.guid.prefix);
+        }
+        m = ddsrt_avl_iter_next (&iter);
       }
-      m = ddsrt_avl_iter_next (&iter);
     }
-  }
 
-  update_qos_locked (&pwr->e, pwr->c.xqos, xqos, timestamp);
+    update_qos_locked (&pwr->e, pwr->c.xqos, xqos, timestamp);
+  }
   ddsrt_mutex_unlock (&pwr->e.lock);
 }
 
-void update_proxy_reader (struct proxy_reader *prd, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp)
+void update_proxy_reader (struct proxy_reader *prd, seqno_t seq, struct addrset *as, const struct dds_qos *xqos, nn_wctime_t timestamp)
 {
   struct prd_wr_match * m;
   nn_guid_t wrguid;
@@ -4125,49 +4130,53 @@ void update_proxy_reader (struct proxy_reader *prd, struct addrset *as, const st
   memset (&wrguid, 0, sizeof (wrguid));
 
   ddsrt_mutex_lock (&prd->e.lock);
-  if (! addrset_eq_onesidederr (prd->c.as, as))
+  if (seq > prd->c.seq)
   {
-    /* Update proxy reader endpoints (from SEDP alive) */
-
-    unref_addrset (prd->c.as);
-    ref_addrset (as);
-    prd->c.as = as;
-
-    /* Rebuild writer endpoints */
-
-    while ((m = ddsrt_avl_lookup_succ_eq (&prd_writers_treedef, &prd->writers, &wrguid)) != NULL)
+    prd->c.seq = seq;
+    if (! addrset_eq_onesidederr (prd->c.as, as))
     {
-      struct prd_wr_match *next;
-      nn_guid_t guid_next;
-      struct writer * wr;
+      /* Update proxy reader endpoints (from SEDP alive) */
 
-      wrguid = m->wr_guid;
-      next = ddsrt_avl_find_succ (&prd_writers_treedef, &prd->writers, m);
-      if (next)
-      {
-        guid_next = next->wr_guid;
-      }
-      else
-      {
-        memset (&guid_next, 0xff, sizeof (guid_next));
-        guid_next.entityid.u = (guid_next.entityid.u & ~(unsigned)0xff) | NN_ENTITYID_KIND_WRITER_NO_KEY;
-      }
+      unref_addrset (prd->c.as);
+      ref_addrset (as);
+      prd->c.as = as;
 
-      ddsrt_mutex_unlock (&prd->e.lock);
-      wr = ephash_lookup_writer_guid (prd->e.gv->guid_hash, &wrguid);
-      if (wr)
+      /* Rebuild writer endpoints */
+      
+      while ((m = ddsrt_avl_lookup_succ_eq (&prd_writers_treedef, &prd->writers, &wrguid)) != NULL)
       {
-        ddsrt_mutex_lock (&wr->e.lock);
-        rebuild_writer_addrset (wr);
-        ddsrt_mutex_unlock (&wr->e.lock);
-        qxev_prd_entityid (prd, &wr->e.guid.prefix);
+        struct prd_wr_match *next;
+        nn_guid_t guid_next;
+        struct writer * wr;
+
+        wrguid = m->wr_guid;
+        next = ddsrt_avl_find_succ (&prd_writers_treedef, &prd->writers, m);
+        if (next)
+        {
+          guid_next = next->wr_guid;
+        }
+        else
+        {
+          memset (&guid_next, 0xff, sizeof (guid_next));
+          guid_next.entityid.u = (guid_next.entityid.u & ~(unsigned)0xff) | NN_ENTITYID_KIND_WRITER_NO_KEY;
+        }
+
+        ddsrt_mutex_unlock (&prd->e.lock);
+        wr = ephash_lookup_writer_guid (prd->e.gv->guid_hash, &wrguid);
+        if (wr)
+        {
+          ddsrt_mutex_lock (&wr->e.lock);
+          rebuild_writer_addrset (wr);
+          ddsrt_mutex_unlock (&wr->e.lock);
+          qxev_prd_entityid (prd, &wr->e.guid.prefix);
+        }
+        wrguid = guid_next;
+        ddsrt_mutex_lock (&prd->e.lock);
       }
-      wrguid = guid_next;
-      ddsrt_mutex_lock (&prd->e.lock);
     }
-  }
 
-  update_qos_locked (&prd->e, prd->c.xqos, xqos, timestamp);
+    update_qos_locked (&prd->e, prd->c.xqos, xqos, timestamp);
+  }
   ddsrt_mutex_unlock (&prd->e.lock);
 }
 
@@ -4219,7 +4228,7 @@ int delete_proxy_writer (struct q_globals *gv, const struct nn_guid *guid, nn_wc
 
 /* PROXY-READER ----------------------------------------------------- */
 
-int new_proxy_reader (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const nn_plist_t *plist, nn_wctime_t timestamp
+int new_proxy_reader (struct q_globals *gv, const struct nn_guid *ppguid, const struct nn_guid *guid, struct addrset *as, const nn_plist_t *plist, nn_wctime_t timestamp, seqno_t seq
 #ifdef DDSI_INCLUDE_SSM
                       , int favours_ssm
 #endif
@@ -4239,7 +4248,7 @@ int new_proxy_reader (struct q_globals *gv, const struct nn_guid *ppguid, const
   }
 
   prd = ddsrt_malloc (sizeof (*prd));
-  proxy_endpoint_common_init (&prd->e, &prd->c, EK_PROXY_READER, guid, timestamp, proxypp, as, plist);
+  proxy_endpoint_common_init (&prd->e, &prd->c, EK_PROXY_READER, guid, timestamp, seq, proxypp, as, plist);
 
   prd->deleting = 0;
 #ifdef DDSI_INCLUDE_SSM