Stop Materials from Overlapping on Model

Hi I’m very new to Blender and any advice I could get on my project would be much appreciated. I’m trying to highlight different body parts on a spinning makehuman model. The way I approached this (with my very limited Blender knowledge) was to select a body part I wanted to highlight, key it to the original model’s color so that it wasn’t noticeable for the time that it wasn’t highlighted, key it’s color to pink at the point of the timeline when i wanted it highlighted, move forward 90 frames, key it pink again so it didn’t gradient, and then move forward another frame to key it to the og models color. This was working well until body parts started overlapping (e.g. the ‘thigh’ material would overlap with the ‘whole leg’ and cancel it out when i wanted to look at the whole leg).

I’m not allowed to post attachments so here’s an imgur of what I’m trying to do:

Does anyone have any suggestions on how to approach this problem or perhaps a better way of making this animation in the first place? Thanks!

You just need more materials-- like, both “thigh” material and “leg except for thigh” materials. If you wanted to change “leg”, you would change both.