I had a similar idea 💡 in spriit to your idea but it was more simplified in concept to what you are talking about I written in https://taylorapplebrook.itch.io/second-helpings/devlog/1306776/what-should-be-the-focus-of-major-content-update-4.
To summarize the idea 💡 centered around veteransy & the girls gaining a Veteran feede tag with the girl eating whatever you feed them like a base feeder persona & gain new dialogue with interactions. This would happen when one has the talk about Life-O-suction to reset their gains to do it all over again.
I like your idea MeeperMooper were different personas have some positive or negative interactions on top of their unique dialogue that you unlock with weight progression, I do feel from my understanding the game design that it would be more it's difficult to do then a verbial chickpoint that brings the change would be easier. Of course it will ultimately be up to the Dev.