My slabs/flakes are the average size that falls off the average square bale.. they don't really come in sizes here, they are all the same
I usually feed the two separately, our barn is a open double box stall that they go in and out as they please, so she gets fed inside with her hay and the pony is fed outside with his hay and grain, but if its raining/snowing I can't feed him outside obviously, so they get their hay together with grain, which I scoop with a plastic solo cup about a inch from the bottom full, sprinkled over the hay.
I have tried to lunge her, and she refuses to, but I am not very experienced with it since my pony doesn't do it either.
But any exercise we do is me moving with her. I run regularly anyway, so I don't have a problem getting her to get going beside me. We practice commands, and run up and down the hills. Maybe I can use some of my ponies Agility equipment to play with her.
I also have an issue getting her past a walk when I ground drive her, She works great when I am next to her and ask for a trot, she has a nice light controlled trot, she responds to my lead, I ask her to take it down a notch she eases and everything is great, but when I am behind her, its like she only knows walk
So that's frustrating, But I will try to work her in hand more often getting her to run with me maybe.