I would not worry about it.. they are not territorial in the way a robin or hawk are, they only defend around the nest for most parts. Just feed them inside, or were the Ferals can not see the feed. I see no problem.Dave
I agree with Rod, plus the fact that with an open loft, you are inviting predators to visit as well.There should be no problem except the following that I can think of:
1.) Those feral will end up joining your flock and ends visiting your loft. So if they are carrying diseases, then your birds are exposed as well.
2.) Your birds might end joining them and leave your place.
I experienced #2 and my friend did too. I have no experience with #1 so that is just a wild guess and pessimistic view. Usually ferals, like any wild birds, are healthy.