Hi there.
If you have enough hens so that he does not concentrate only on one you should be ok.
I would suggest though that you house your hens separately for a while.
Let the new and old girls get used to each other, let them settle in and lay properly so they know where the feed and water is, bed etc.
Then after a week, introduce the male and watch them carefully.
it should be ok, as long as you always introduce the male to the females, and not toss females into the cock run.
It is more important for the girls to get along, they can be real bitches, and for them to be settled than it is for the cock.
M