No. I can't imagine that would be good. There are circumstances where young bachelors are all turned out together, but they are all the same age. Your adult stallion is not compatible with foals. He should remain alone now until he's gelded. Stallions are not good companions to other horses, even 'good' ones. If he were in the wild, his instinct would be to drive the competition from herd.
OK i thought that would be a big NO, Sense told me that thee foals could get hurt, but I wasn't sure how it worked in the wild. Anyway, we have worked out what we are going to do, when the time comes the foals can stay in the field they are used too. The mares can go in a new one.
Thunder and Adge only seem to be with the mares when they want milk, which does not seem that often. They drink water and eat hay and grain already and mostly stay by themselves away from MOMS! : ) We will cut back on Mistys and Sugars intake a week before total seperation so that their milk will slow down some.
We are already making sure the foals get what they need in the way of grain and hay by seperating them at feeding times.