I did something similar in Carrara with a sexy girl turning into a Lycan, ofcourse Carrara has animated textures!
so it was quite simple to save a global shader based on V4’s uv’s in both MS Lycan’s textures and in my case Reby Sky then create a layered shader and transition between the two.
one could do it in studio with two figures occupying the same space with the same animation and Casual’s Matanim script on the opacity channel of each I guess if one did not wish to do it postwork.
not scary, you will find the script in RichHaseltines list
you just load it and check opacity animatable as true on the little chart that opens
then along the timeline adjust the parameters in surfaces
same with colour, displacement bump etc, all can be animated.