How do I select child when parent and child is the same object type?

I have a bunch of sprites called MoveMapper, they are all children in a chain.

Something like this: P->C->C->C->C->C

I start at P, run some code, and if a boolean is true I select the child and call the same function with the UID of the picked child.

Not working:

However, MoveMapper trying to pick children of MoveMapper-type does not work.

I have found the work-around using families, and it works. But I'm not fond of that solution, perhaps someone here have a nice alternative where faimilies are not used?

Working work-around.