I haven’t asked - but can’t imagine they would have anything green to eat right now. Around here, any animal „on pasture“ just has dry grass and weeds to eat if there’s anything left to munch on at all. I imagine that’s why she is feeding alfalfa. Here the summer is hay eating season... At our place they will go in the back horse pasture, which is mostly dry wild oat grass now. It’s quite tall and I don’t believe they will eat much of that, do you?
Anyway, so what I‘m hearing is that switching from alfalfa to grass hay is fine - correct? And that they are old enough to drop the sheep keeper feed? Maybe I‘ll keep a little around for a training treat?
Should I give any supplements besides the salt lick and baking powder made available? Something that might balance out whatever they are not getting from the hay?
Mine eat all the leafy parts and seedheads, leaving the bare stems for me to deal with.

I can't even put 5 ponies on 0.3-0.4 acres of stems, because they'll still get fat off it...So I mow the stems.
What breed are they? Should of asked that first. Babydoll should do fine on grass or grass hay/pellets alone, but other breeds may need more protein or in general a lot more food intake than others. My Corriedale had to be free fed alfalfa pellets, while my BFL/Cheviot was fine on pasture with the Babydolls. Their Babydoll crossed mutt lambs have been fine treated like Babydoll.
Complete feeds should have all the minerals they need, but I'm assuming that from experience with horse feeds. Idk if it's true for sheep feed. If it is, then you wouldn't need to feed much else, besides loose hay for gut mobility.
I've switched to Kalmbach sheep mineral vs premier1 sheep mix this year. No more mixing plain salt with the minerals, yay. It's salt and minerals together, ready to pour into buckets. It also has something in it which helps with selenium absorption.
I feed pasture, grass or alfalfa pellets and hay, not complete sheep feed, so they need the minerals in the salt. Yours might not need it if fed the complete feed, but then you'd have to follow the bag for pounds of feed a day per sheep to equal the right amount of vits and minerals.