I’m running into this now. I wanted to create a custom set of box collisions that could be configured, but I had to end up putting them in an Actor and referencing them as ChildActorComponents (which involves some clunky casting to get at it’s member variables and functions). Being able to use a PrimitiveComponent as a parent in Blueprints would be nice.
It looks like you can select it as a parent when making a new C++ class though 