I think it would be fun to see these 3 together. Myne and Mile the 2 totally normal average girls with the quieter White. All 3 have tendencies to quote strange or obscure things. Myne and Mile also have their book making/writing fantasies.
2 - The magic / Adventure group
Making Magic - Chise
Death March to another world - Satou
They both love magic and wondering around sightseeing. I would love to see Satou and Chises worlds combine. Satous *ions meeting Chises *riels, Nana and Teto helping little ones and begging their masters for food.
Think of all the taste Morsels in another world, we shall combine worlds! Karion and Lariel say so too.
I would like to see Mushroom Princess Miabell Luna Tearmoon setting out on an expedition from Miatown and finding through some shenanigans the portal gate to Rosemyne's Alexandria. From there there would be clashing ideologies between the blind faith of Miabelle's followers and the extreme competency of Rosemyne's. All while Mia and Myne are happily exchanging ideas and generally getting along like a house on fire.
Honestly I just don't remember if Miatown had a port or not? But thanks to Alexandria's portal gate this is something that could easily be written around: "Suddenly a magical gate appeared in Miatown with a vast body of water on the other side. Mia had a ship build and set out to explore the town visible in the distance. The lure of new and tasty snacks was just too stong to resist."