How do you attach one mesh to another in Blueprint?

I know questions like this have been asked before. And so far, I’ve found no way that works.

I’d like to attach the above skeletal ship mesh - which is properly physically set up, collision and yada yada - to the octagon below it. The octahedron? octagon? is being constrained in the z-axis at the moment as it just stops balloon flight from happening till I get intelligent thruster compensation going.

The thrusters and stuff all fly and fire as required:

But as you can see, the ship is not attached, nor is it parenting in any way. It acts like a physics object should, and is pushed up by the platform below it. Is there a specific method I need to use to parent the ship’s location to the platform below it? I can’t figure it out.