Hi and Welcome to BYC, and congrats on the 2 new ducklings and the 2 new to come any day. As far as keeping them together, I think it would be better for the newly hatched if you put some kind of separation in the brooder so the youngest can get on their feet before being introduced to the older ones, a week makes a big difference in ducklings. The separation should be something where they can see each other but the older ones won't be able to pick on the younger ones, then after a few days give supervised play time where they can all be together but your there to stop any picking, I would have the largest brooder you can find so they have plenty of room to spread out, being cramped can cause the older ones to pick on the younger also. Do you have homes already for these ducklings? we love love to see pics of your set up and class room with the children enjoying these little ducklings. I know they are enjoying them. All the best.
