I was referring to this comment. You mentioned doing a line trace to get an index (?) to the specific piece and then manipulate its transform. I am trying to figure out how to get to that specific piece like you mention.
— Edit
Oh wait, are you saying you created your own implementation of a geometry collection? If so I misunderstood your post. I thought you were saying you used your own extension of geometry collection.
Making your own GC implementation makes more sense and is something I was considering as well.