diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index 0402cc2a206..fc582e02d94 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -19132,31 +19132,6 @@ void Player::SendSavedInstances()
     }
 }
 
-/// convert the player's binds to the group
-void Player::ConvertInstancesToGroup(Player* player, Group* group, bool switchLeader)
-{
-    // copy all binds to the group, when changing leader it's assumed the character
-    // will not have any solo binds
-
-    for (uint8 i = 0; i < MAX_DIFFICULTY; ++i)
-    {
-        for (BoundInstancesMap::iterator itr = player->m_boundInstances[i].begin(); itr != player->m_boundInstances[i].end();)
-        {
-            if (!switchLeader || !group->GetBoundInstance(itr->second.save->GetDifficulty(), itr->first))
-                group->BindToInstance(itr->second.save, itr->second.perm, false);
-
-            // permanent binds are not removed
-            if (switchLeader && !itr->second.perm)
-            {
-                // increments itr in call
-                player->UnbindInstance(itr, Difficulty(i), false);
-            }
-            else
-                ++itr;
-        }
-    }
-}
-
 bool Player::Satisfy(AccessRequirement const* ar, uint32 target_map, bool report)
 {
     if (!IsGameMaster() && ar)
diff --git a/src/server/game/Entities/Player/Player.h b/src/server/game/Entities/Player/Player.h
index 672ce2a4746..a2602bb94c0 100644
--- a/src/server/game/Entities/Player/Player.h
+++ b/src/server/game/Entities/Player/Player.h
@@ -2406,7 +2406,6 @@ class Player : public Unit, public GridObject<Player>
         bool HasPendingBind() const { return _pendingBindId > 0; }
         void SendRaidInfo();
         void SendSavedInstances();
-        static void ConvertInstancesToGroup(Player* player, Group* group, bool switchLeader);
         bool Satisfy(AccessRequirement const* ar, uint32 target_map, bool report = false);
         bool CheckInstanceValidity(bool /*isLogin*/);
         bool CheckInstanceCount(uint32 instanceId) const;
diff --git a/src/server/game/Groups/Group.cpp b/src/server/game/Groups/Group.cpp
index c86057a9ac1..565952caf0f 100644
--- a/src/server/game/Groups/Group.cpp
+++ b/src/server/game/Groups/Group.cpp
@@ -148,10 +148,9 @@ bool Group::Create(Player* leader)
 
         CharacterDatabase.Execute(stmt);
 
+        Group::ConvertLeaderInstancesToGroup(leader, this, false);
 
         ASSERT(AddMember(leader)); // If the leader can't be added to a new group because it appears full, something is clearly wrong.
-
-        Player::ConvertInstancesToGroup(leader, this, false);
     }
     else if (!AddMember(leader))
         return false;
@@ -406,9 +405,7 @@ bool Group::AddMember(Player* player)
         player->SetGroup(this, subGroup);
 
     // if the same group invites the player back, cancel the homebind timer
-    InstanceGroupBind* bind = GetBoundInstance(player);
-    if (bind && bind->save->GetInstanceId() == player->GetInstanceId())
-        player->m_InstanceValid = true;
+    player->m_InstanceValid = player->CheckInstanceValidity(false);
 
     if (!isRaidGroup())                                      // reset targetIcons for non-raid-groups
     {
@@ -685,7 +682,7 @@ void Group::ChangeLeader(ObjectGuid newLeaderGuid)
         }
 
         // Copy the permanent binds from the new leader to the group
-        Player::ConvertInstancesToGroup(newLeader, this, true);
+        Group::ConvertLeaderInstancesToGroup(newLeader, this, true);
 
         // Update the group leader
         PreparedStatement* stmt = CharacterDatabase.GetPreparedStatement(CHAR_UPD_GROUP_LEADER);
@@ -711,6 +708,42 @@ void Group::ChangeLeader(ObjectGuid newLeaderGuid)
     BroadcastPacket(&data, true);
 }
 
+/// convert the player's binds to the group
+void Group::ConvertLeaderInstancesToGroup(Player* player, Group* group, bool switchLeader)
+{
+    // copy all binds to the group, when changing leader it's assumed the character
+    // will not have any solo binds
+    for (uint8 i = 0; i < MAX_DIFFICULTY; ++i)
+    {
+        for (Player::BoundInstancesMap::iterator itr = player->m_boundInstances[i].begin(); itr != player->m_boundInstances[i].end();)
+        {
+            if (!switchLeader || !group->GetBoundInstance(itr->second.save->GetDifficulty(), itr->first))
+                group->BindToInstance(itr->second.save, itr->second.perm, false);
+
+            // permanent binds are not removed
+            if (switchLeader && !itr->second.perm)
+            {
+                // increments itr in call
+                player->UnbindInstance(itr, Difficulty(i), false);
+            }
+            else
+                ++itr;
+        }
+    }
+
+    /* if group leader is in a non-raid dungeon map and nobody is actually bound to this map then the group can "take over" the instance *
+    * (example: two-player group disbanded by disconnect where the player reconnects within 60 seconds and the group is reformed)       */
+    if (Map* playerMap = player->GetMap())
+        if (!switchLeader && playerMap->IsNonRaidDungeon())
+            if (InstanceSave* save = sInstanceSaveMgr->GetInstanceSave(playerMap->GetInstanceId()))
+                if (save->GetGroupCount() == 0 && save->GetPlayerCount() == 0)
+                {
+                    TC_LOG_DEBUG("maps", "Group::ConvertLeaderInstancesToGroup: Group for player %s is taking over unbound instance map %d with Id %d", player->GetName().c_str(), playerMap->GetId(), playerMap->GetInstanceId());
+                    // if nobody is saved to this, then the save wasn't permanent
+                    group->BindToInstance(save, false, false);
+                }
+}
+
 void Group::Disband(bool hideDestroy /* = false */)
 {
     sScriptMgr->OnGroupDisband(this);
diff --git a/src/server/game/Groups/Group.h b/src/server/game/Groups/Group.h
index 40d796f043d..0595782742d 100644
--- a/src/server/game/Groups/Group.h
+++ b/src/server/game/Groups/Group.h
@@ -198,6 +198,7 @@ class Group
         bool   AddMember(Player* player);
         bool   RemoveMember(ObjectGuid guid, const RemoveMethod &method = GROUP_REMOVEMETHOD_DEFAULT, ObjectGuid kicker = ObjectGuid::Empty, const char* reason = NULL);
         void   ChangeLeader(ObjectGuid guid);
+ static void   ConvertLeaderInstancesToGroup(Player* player, Group* group, bool switchLeader);
         void   SetLootMethod(LootMethod method);
         void   SetLooterGuid(ObjectGuid guid);
         void   SetMasterLooterGuid(ObjectGuid guid);
diff --git a/src/server/game/Maps/Map.cpp b/src/server/game/Maps/Map.cpp
index d839f550405..a9f3710a385 100644
--- a/src/server/game/Maps/Map.cpp
+++ b/src/server/game/Maps/Map.cpp
@@ -3031,7 +3031,7 @@ bool InstanceMap::AddPlayerToMap(Player* player)
             {
                 if (group)
                 {
-                    // solo saves should be reset when entering a group
+                    // solo saves should have been reset when the map was loaded
                     InstanceGroupBind* groupBind = group->GetBoundInstance(this);
                     if (playerBind && playerBind->save != mapSave)
                     {
diff --git a/src/server/game/Maps/MapInstanced.cpp b/src/server/game/Maps/MapInstanced.cpp
index f8fa36a20ea..d83d88ba87c 100644
--- a/src/server/game/Maps/MapInstanced.cpp
+++ b/src/server/game/Maps/MapInstanced.cpp
@@ -163,7 +163,11 @@ Map* MapInstanced::CreateInstanceForPlayer(const uint32 mapId, Player* player, u
             {
                 groupBind = group->GetBoundInstance(this);
                 if (groupBind)
+                {
+                    // solo saves should be reset when entering a group's instance
+                    player->UnbindInstance(GetId(), player->GetDifficulty(IsRaid()));
                     pSave = groupBind->save;
+                }
             }
         }
         if (pSave)