Hello,
The automatic translation makes it a bit difficult to understand the exact problem, could you also post screenshots of the errors?
By design all the head versions should go in the head slot, in a slot only one attachment can be visible at a time. Do you need multiple heads being displayed at the same time? if that is the case maybe you want each head to be in its own slot.
I can't give better advice beyond what I was able to gather from the posted info, but I hope this may still be useful.
