I frequently brood chicks, keets and poults together. I always feed all of them the turkey game bird starter (28% protein) that the keets and poults need. I have never seen any sign that the higher protein feed hurts the chicks but it definitely helps the keets and poults.
If they are all still together when I switch to grower then I use the turkey game bird grower or a meat bird grower since both are very close in protein content.
As adults my turkeys and chickens are together and both get 16% protein layer pellets with free choice oyster shell. I tried the housing of guineas, chickens and turkeys together and the guineas caused to much stress on the chickens and turkeys so my adult guineas are housed separately and as adults they get 20% protein layer pellets and free choice oyster shell.
Good luck.