I have a quite large BLR rooster who right now has one girlfriend, a SLW. I bought him 2 BLR girls. RIght now they are seeing each other through wire during the day, he dances constantly for them. Due to his large size, I think waiting until the girls are the same size as the SL might be best. But, generally speaking. at what age is a good age to add young pullets in with a mature roo and year old hen? These two are about 16 weeks old, give or take a week, as they aren't from the same hatch. one is older by a week.