Basic question about blueprint components

I am trying to get into writing blueprints but I keep running into one little issue that keeps tripping me up, and I feel like I am just missing some basic knowledge to understand it. I checked the blueprint components section of the UE4 documentation but it doesn’t really get into it, hopefully someone can clear this up for me.

Basically, every time I make a new blueprint, the main object is always the parent of everything else in the blueprint. For example I am trying to make a door, and unthinkingly I just selected the door mesh and created blueprint. Then I added a collision box, set it up to open the door, tested it, and it works… sort of. The collision box moves up with the doorway because it is inheriting it’s relative location, (or it is child to the doors parent, whatever the correct terminology is) so the door opens partway until the triggering object isn’t in the collision box anymore, then it just bounces there. The specifics are not really important, and I know I can fix this pretty easily with workarounds, but why can’t I just move the collision box out from under the hierarchy of the main component? It seems to me like I should be able to create a second parent category and put the collision in that, or just tell it some other way not to inherit the relative location of the main component when it moves.

In another blueprint I had the brilliant idea to just make the main component blank. I removed the mesh from the main component and added a new component and made that the object I wanted to manipulate. Then when I added new components, they were at the same hierarchy level as the new “main” component and everything worked perfectly independently. I could child the things I wanted to, and have independent the things I wanted as well. The only problem is that every time I build the level it throws an error that the main component of that BP is blank, as if that is a major oversight. I KNOW it is blank, I did it on purpose, but since it is warning me about it I assume that clearly isn’t the correct way to deal with this.

This is a long winded post for hopefully what is a very simple solution that I have overlooked. I just can’t for the life of me seem to find an answer online nor figure it out myself. Or perhaps this is just the way it works and I am thinking about this all wrong and need to approach creating blueprints from a different angle. Any help clearing up my lack of understanding with this issue would be greatly appreciated!