It's difficult isn't it?!
My rabbit Sylar is on a pellet free diet and his bonded friend needs pellets because he's a skinny boy. We have to feed them separately now because Sy would charge at Hiro and because he has balance issues (head tilt) he would knock him over I just wait until they are in different rooms and then shut the door. I give Hiro his pellets and my o/h gives Sy some dried forage so he doesn't feel like he's missing out!