I've played this game for only a couple times, but I could never find the other girls in said game.
Also not sure if you actually CAN customize how they look.
Viewing post in The Tale of Ebony Floe Preview Demo Version 3 comments
They will only spawn at random times of the day (though they are guaranteed to spawn at lunch time), so you will need to make the clock run for a bit (mainly by collecting Insight tokens throughout the map)
The crop top can only be bought for Ebony for now, as I still need to fix up the meshes for the other girls ^^;