You are right. I added the node_attach definition and now the get attached in the right direction. Thank you very much. However the y-value for the node_attach has to be lower than the one in node_stack_bottom. For the stock docking port Sr. it seems substracting 0.05 works pretty well but for the ports from NearFutureConstruction this is too much difference. I have to figure out what the right value for them would be. You could try to make the parts you want to attach the ports to container bays and the ports containers. This way they will get forced to attach in a specific direction if you "store" them. Not the best way and you will have to modify some parts but I think this could work. Did this with the girder segments to be able to build larger structures in space.