I ordered 5 guineas with some day old chicks. Raised them together. One was dead on arrival, another was sickly and died soon after arrival. A third keeled over suddenly in the brooder. Ended up with a pair. The female was dead in the run for no apparent reason one day in the summer.
She had good wait and no marks on her, checked she wasn't eggbound. I never did figure out what went wrong. The surviving male of the bunch has been living with the chickens and seems to be doing fine.
I think as long as you don't have just ONE.you will be fine, I do want to say though......be sure not to have too many males than females........... better off with more females than males...... good luck.........I loved having my Guineas