My idea was to use the selected bone in the top image, to control where he was facing in the game (those two are currently connected by -100 relative coordinate transform)

But when going to a side, then one cheek bone need to stand still, while the center follows and the other cheek follows a bit behind .. but what do I do when I need to go the other way, as the bone on the other side need to stop at its start position??
How do I stop bones from moving too far from the center?
Edit: Maybe there isn't a good way to do this from 1 point to both sides?
After a bit of thinking.. Since I get one side to work, then the easiest might be to just flip it for the other side..
I do have some images that should be on a spesific side of the head, but I guess I could add a hidden copy on the other side and toggle visibility when the flip happens.
Non drawn stuff don't have to calculate their mesh transform I hope.
(version 3.7.96 due to GameMakerStudio 2, in case that matters)