source/blender/blenkernel/intern/node_runtime.cc

@@ -130,7 +130,7 @@ static void update_directly_linked_links_and_sockets(const bNodeTree &ntree)
       std::sort(socket->runtime->directly_linked_links.begin(),
                 socket->runtime->directly_linked_links.end(),
                 [&](const bNodeLink *a, const bNodeLink *b) {
-                  return a->multi_input_socket_index > b->multi_input_socket_index;
+                  return a->multi_input_socket_index < b->multi_input_socket_index;
                 });
     }
   }

source/blender/blenkernel/intern/node_tree_update.cc

@@ -667,9 +667,7 @@ class NodeTreeMainUpdater {
       link.tonode = &node;
       link.tosock = to_socket;
       link.flag |= NODE_LINK_VALID;
-      const int internal_multi_input_socket_index = from_socket->directly_linked_links().size() -
-                                                    1;
-      link.multi_input_socket_index = internal_multi_input_socket_index;
+      link.multi_input_socket_index = 0;
       node.runtime->internal_links.append(link);
     }
     BKE_ntree_update_tag_node_internal_link(&ntree, &node);

source/blender/editors/space_node/drawnode.cc

@@ -1595,8 +1595,11 @@ static float2 socket_link_connection_location(const bNode &node,
 {
   const float2 socket_location = socket.runtime->location;
   if (socket.is_multi_input() && socket.is_input() && !(node.flag & NODE_HIDDEN)) {
+    /* If link didn't connected to socket. In this case, at less this link have to be counted in
+     * the list as single one. */
+    const int total_inputs = math::max<int>(1, socket.runtime->total_inputs);
     return node_link_calculate_multi_input_position(
-        socket_location, link.multi_input_socket_index, socket.runtime->total_inputs);
+        socket_location, link.multi_input_socket_index, total_inputs);
   }
   return socket_location;
 }

source/blender/editors/space_node/node_edit.cc

@@ -112,7 +112,7 @@ float2 node_link_calculate_multi_input_position(const float2 &socket_position,
 {
   const float offset = (total_inputs * NODE_MULTI_INPUT_LINK_GAP - NODE_MULTI_INPUT_LINK_GAP) *
                        0.5f;
-  return {socket_position.x, socket_position.y - offset + index * NODE_MULTI_INPUT_LINK_GAP};
+  return {socket_position.x, socket_position.y + offset - index * NODE_MULTI_INPUT_LINK_GAP};
 }
 
 static void compo_tag_output_nodes(bNodeTree *nodetree, int recalc_flags)

source/blender/editors/space_node/node_relationships.cc

@@ -309,7 +309,7 @@ static void sort_multi_input_socket_links_with_drag(bNodeSocket &socket,
   });
 
   for (const int i : links.index_range()) {
-    links[i].link->multi_input_socket_index = i;
+    links[i].link->multi_input_socket_index = links.size() - 1 - i;
   }
 }