I had mine in seperate brooders, side by side rubber made totes with a screen frame on top and a heat lamp in between them. until they were about a month old. Then I stuck them all in the coop and run together.
They still live together.
I tried separating them and they all threw major fits.
I did lost 1 chick to the ducks pool.
As messy as the ducks were, constantly spilling their water, I would keep them separate. That or build a raised bottom in the brooder so when the duckies spill no one ends up standing in water, wet bedding, etc.