On the small ones you will need to put some deer netting or something over the top of the run if you can, the little ones fly out early and when alone they may not make it back.. When in the flock they are always watching as a group, when young and alone they are more susceptible to the hawk...
My guineas roost and stay in the same run as my chickens so far no problems, we will see what spring brings. I had to put some deer netting over the top of the run, because they fly well even at a young age and will fly out.
I have 6 guineas that i added in after my chickens. They adapted well with the rest of the flock, I fenced off a small area in my run with a small hole for the guineas to pass through so that they could get away from the rest of the flock in the run. They have always come back to the coop...