They are like the BB Whites... too big to do the deed. You can crossbreed (heritage tom w/BB hen), but I would collect the eggs and either put them under another bird or incubate them. Otherwise she might crush the eggs. I have a BBB hen this year that I will be attempting to cross with a White Holland. Should be interesting... if my birds ever start laying
Most BB turkeys breast get in the way so they can't mount the females correctly, Also because of the male size they can seriously hurt the hens. So Natural breading is not usually done. They can but the fertility rate is so low its best not to, so artificial insemination is usually always used. Although we never let a BB hen go broody, the hens are larger then a heritage hen so then may damage the eggs or hurt young poults.