I threw a handful in for them they seemed ok with it. So I will just mix as I go along.Or, as they get bigger, mix it in with the current bag of starter. In a couple (2 to 3) weeks, they will be so much bigger that they might be fine with the larger crumbles.
Again, in a couple of weeks, mix some in with what you are feeding now, and if they eat it, great! Keep doing it. If not, then whatever is in it, they don't like.
I had them outside for about 10 min yesterday, it was nice and warm, but I think the sun was too hot for them, they had a blast eating dirt and picking at grass.
Henny Penny came to have a look and was making sounds like she might want to be a mum, but they have imprinted me so that's not likely to happen.