Converse problem: How to apply same set of 3~~4 texture maps to many objects when an import breaks to umpteen sub-rigs ??

This was sorta-solved when horrified artist re-exported their FBX 2018 (v7.5) model as 'optional' FBX 2013 (v7.3).

But, I'd been facing 100++ sub-rigs. Tedious enough parenting them a dozen at a time to a 'dummy' place-holder via hierarchy window...

Until artist did fix, my best hope was to convert model to OBJ, still with those 100++ parts and their 'use mtl' calls, use word-processor to search / replace...