I have successfully kept a Guinea Hen(s) with my chickens with no problem. I had two originally and one died so she was left as the only Guinea for about 3 years. I have a mixed flock of chickens, Muscovy, and now 4 Guineas. I took 3 keets from my mom, and they all turned out to be males. Now Fred (Guinea Hen) has three husbands and they still live with the mixed flock. I think the key is they need to be raised with chickens- and they need to have space to roam. The hens have been less attitude-y in my experience. They do go off and roam on their own during the day, but come back to roost every night. When it was just Fred in the flock she actually preferred the ducks since that was what she was raised with since I got her at the same time as some ducklings. This is kind of jarbled, so sorry. Basically, it can be done, but you need the space, and to start with keets mixed with young of the species you are keeping them with.
Edited to add, I have had ZERO luck getting adult Guinea's to stay at my property IF introduced as adults. They take a long time to acclimate to a new place, and if they aren't going to be kept in containment have always disappeared. I've tried twice with adults from my parents house, and every time I have ended up with only Fred. that is why I brought keets over, and they have been at my house for about year now. so unless you are able to keep one locked up for quite a while, it's hard to get them to see the new place as home.