I'm currently trying to make a two stage ship. The first stage is an atmospheric plane, which would carry the actual spaceship up to the edge of the atmosphere, like SpaceShipOne. I've tried a lot of methods short of just strutting the two together and sticking separation boosters to tear them apart, but I can't figure out how to use docking ports to join the two ships together so I can just release it at altitude. I've been able to join two docking ports together, using the ALT key, but I have not been able to attach the second docking port to a fuselage piece. I'm not sure what I'm missing.