I think there is a way to edit the appearance_info.RDAT file inside the png.iff to display the alt hair in different scenarios.
IIRC you can set up that appearance_info.RDAT to display the primary hair when no head band is worn, then display alternate hair when the headband is worn. Example. De'angelo Russell.

I know you can go even further then that assigning hats, headphones, tie handbands, and more just using appearance_info.RDAT
I don't know much more then that. I haven't checked into it in weeks.