I was thinking that perhaps it could be a sort of role switch/ personality swap thing.
I like the idea of Jon swapping roles with his mom and other people swapping with others. I'm not sure if I want to include body transformations though. I like more the mental swaps.
I realise that what I'm describing is similar to the Slowly Swapping story but I quite like the idea of using someone to hypnotise a person or using the sessions in your branch.
We could use Miss Fine as the antagonist.
So for example we could have Jon and Linda swap roles with each where Jon becomes the mom.
If you think we should include body transformations then that's fine but I will add chapters that mostly focus on the mental changes
Hope that makes sense