Here’s how I got the chinstraps without the top of the headgear:
This caused some problems with facial scars, which need to be below the headgear but above both head layers, so Anvils 2 and 3 actually have identical scar layers in the same place and just masked slightly differently. One is sandwiched between the lower head layer (marked in red) and the headgear, the other is on top of the upper head layer (marked in blue)
