It's too soon to wean them. The youngest should be at least 5 months.
Just keep feeding the moms well... there are supplements you can add if they keep dropping... and give as much hay as they want.
The short term separations are good, they can help regulate and know exactly how much each horse is eating and ensure Misty is actually getting what you are feeding her.
Trust me, Misty gets all that she wants! She is the dominant horse and if she wants the colts or Sugars, by God she will go get it! Maybe we should wait on the weaning till Thunder is 5 months, which means 2 months still to go. I will speak to the vet and see if he can't suggest something. I am going to get a full body pic of her now, see u in a bit.
Sharn