I'm trying to launch a ship that consists of two parts docked together, and am using tri-coupler docking to do so (where you put three docking ports on a tri-coupler for increased stability) to keep the ship from wobbling as much. However, there is a reoccurring problem; it seems like I can't attach all three docking ports to both tri-couplers in the VAB. I tried to build it first by putting three ports on a tri-coupler (facing upwards), rotating and placing three ports on top of those, and placing the second tri-coupler to that. It seemed to stay together during flight, but when I got orbit and tried to undock the two parts, tow of the three docking ports on one of the top tri-coupler fell off and floated away.
It looks like you have to attach docking ports DIRECTLY to tri-couplers for them to stay on, so what I did by just placing the tri-coupler on top of three upside-down ports didn't work. I've been fiddling around with this for quite some time and have only managed to attach two ports directly to the top tri-coupler. Does anybody have a way to actually get all three ports to stay on the damn thing?
The docking port structure I'm trying to accomplish:
What happens when I try to move it. The one that stayed on the docking ports falls off in orbit and says "Decouple Node" instead of "Undock" when I right-click it while it is attached to another port.
This would be an easy fix, but some strange stuff happens to the attach nodes when I try to move it: