Oh my! I wouldn’t have anticipated that. I’m also still trying to figure out how to best brood keets to make integration easier. I have a terribly feisty chicken flock, and having hen brooded chicks introduced to the flock has helped decrease stress so much. I’ve been working towards the same for the guineas but they are so challenging! I can only relate my experiences with the two different species: For the chicks, we separate broody hen and chicks in what is essentially a “look but don’t touch” area for the first 1-2 weeks. Then we close off our split run so hen and chicks can mingle more with the flock protected by wire for another 1-2 weeks, then we let them all mingle. Even with subordinate broody hens, this has worked well. For the guineas: we’ve now had three hatches within our coop nests. For the first, moms killed all the hatching keets. Disaster :-( Second hatch: only one egg (I took the others as I didn’t want to see multiple keets killed again!) hatched and other adults kind of eyeballed it oddly like they weren’t sure they would allow it there. However, they did not attack. Moms didn’t really defend it from other adults giving it the stink eye. Moms abandoned after three days, ending that experiment. Third hatch with keets now 2 weeks old: Two newly broody hens stole keets from the hen that patiently hatched them. These two hens (one very dominant) would only let select adults near the recently hatched keets and were very defensive. I observed many antagonist acts from the adults, though I guess they weren’t as awful as it looked as keets survived without apparent damage. As the keets became more mobile, moms became less defensive and keets had more and more adults to interact with. Now other adults just ignore keets, even under challenging circumstances like mealworm feeding.
My take on all of this is that my incubator hatched guineas had no idea what a keet was or that they should be emerging from eggs and defended. My lone broody hatched keet is the first adult to successfully hatch eggs and brood keets, though she did very reluctantly leave them to the keet stealing hens. It took a couple tries and maybe the right bird to recognize keets as new flock members. I do think that mine are getting better with practice.
For you, I’m wondering if your situation is more like our broody chickens, where the other adults have to take on new flock members as an extension of the hen. Is there some way that you can set mom and keets up where they have a “look don’t touch” setup in your guinea coop or run?