Hi there,
We have two ex batts, and our neighbour has a vey butch cockerel , all of them free range and mix together and the ex batts seem to love his "attentions" makes their combs a deeper shade of red! He can get a bit rough at times though , and as has already been said , as long as your girls are fit and healthy , and maybe able to get away from him if they need to as ours can, should be ok.
Mind as I always say there are others on here with FAR more knowledge than me , I can only speak of my own experience.
What a lovely story of the ex batt becoming a mummy ! Anything is possible !
Good luck Ju