Have given up trying. (8+ hours of scouring the internet and trying every option out there does that)
Hope that retropie allows this feature in the future. emulationstation is too rigid in design for my purposes.
I need something with all games on one screen, with no other options for a user to pick at all. Just a basic up/down and select for games. I can show the emulator as data next to gamename/pic/etc – I don’t need different screens for different emulators. Too much choice is a bad thing sometimes and turns off users.