As far as I'm aware there isn't a mod that specifically deals with this; it is possible to do it however, though the person taking it up would have a fair bit of work to get done depending on how far they want to take that with regards to story scenes.
The world map has this issue though where it only handles Cloud, Tifa, and Cid as party leader (doesn't have models for the others and presumably no script for them either). It also loads them based on priority rather than who is the actual party leader (Cloud > Tifa > Cid) so if Tifa was party leader, but Cloud is in the party, it'll load Cloud's model for the world map.