What kind of turkey, Broad-breasted or Heritage? A Broad-breasted can get really big. A Heritage can fly really well. While it may bond with the chickens and stay with them don't be surprised if it perches high in trees or on top of buildings.
Turkeys are generally fed a higher percentage protein feed than chickens. If you are raising her to butcher that could be significant but if you are keeping her as a pet or for eggs it's not that important. She just won't get as big as otherwise.
Blackhead is a poultry disease. It generally kills turkeys but not chickens but chickens can be infected. If you have Blackhead in your chicken flock then the turkey will catch it and die. If Blackhead is not in your flock then the turkey cannot catch it from them. If somebody has Covid or polio then you might catch it form them but if they don't, you can't. Some chicken flocks have Blackhead, some don't.
Is she laying? You should easily be able to tell her egg apart from the chicken eggs, size and eggshell color.