I'm glad to see that someone else has done this. I ordered a batch of guineas from efowl (the special was too good to refuse) and plan on giving them to my broody partridge brahma. She's been desperately trying to hatch her two golf balls for about 3 months now, after being repeatedly taken off the nest and even locked in the "baby house" with all the chicks. (usually does the trick, haha)
So I cracked, and decided to try and give her some guineas. I've been considering it for awhile because of the horrible tick problem we have this year. They should be arriving Wednesday/Thursday, so hopefully she hangs in there another 2 days.