Mirror/symmetrize face sets

I’m starting a character basemesh from separate parts, using a mirror modifier for symmetry. In sculpt mode, I generated face sets from loose parts, but each part of the limbs gets their own face sets, but I want one face set for the shoulders, one for the upper arms, one for the hands, etc. The only solution I’ve found that works is if I create face maps for each symmetrical element, and then initialize face sets from face maps. Is there a faster way to do this?