I must say I have always been impressed with each bew version, but adding other girls and ways to control how they inflate is quite the addition! This is the only version whose notes I read so I can't be too sure of what else is new as well, but I do have a suggestion or two if that's alright.
Perhaps try adding a popping feature to the characters, perhaps when they're getting large enough that they start getting stuck in corners or streetways. If the deflation minigame is too difficult for a player then the best alternative would be to simply keep inflating until they explode. Perhaps a tradeoff would be that their clothes get ripped up or completely fall off, which would not only increase embarassment but also make them passively gain embarassment even while fully deflated.
Another one I would suggest would be more like an easter egg. A hidden little alchemy station full of ingredients that basically gives you master-control of Ebony and her friends' inflation (basically they get sliders for how big and in what way they inflate when they drink a potion). Making it an easter egg would incentivize players to explore and complete missions in order to access it and maybe certain combinations could trigger entirely unique forms of inflation.
Overall it is no exaggeration that this game is coming along very well. I look forward to future updates.