That's just it Tex! As gentle as your older dogs might be, sometimes they can only put up with so much! I know if I had left my pup with either my older Chessie or the Lab, he would have managed to drive them crazy. Pup is little. It doesn't take much of a reaction to hurt or kill pup. I like Nancy Pal's example best. I could let my dogs play unsupervised in the dirt road we live on because none have ever been hurt. BUT I DON'T!
I brought home a new little girl in August. I have 2 boys 4 and 6 at the time. Both neutered. Younger boy adored the girl, older boy bit puppy on face within 2 hours of being in the house. I do not outdoor kennel my dogs, they sleep in the house. The pup learned really quickly to stay away from older boy. Younger boy let's her tear on him and make him cry. I have to keep a leash on her to pull her off of him, he will not defend himself ever with her. She's just terribly mean to him. So I think you might have more problem with the girl being too hard on the boys. Keeping the dynamic intact can be hard. X-pens, crates and leashes can really help you keep the situation under control. As for heat cycles, that's a tough one. Some girls go in heat at 6 months. Some 18 months. Ask the breeder when the mother did, then you'll have a better idea of when to start watching. I check my girl every day. You can see from the photos, she thinks she owns my younger boy. He's like a possession to her.Attachment 13355Attachment 13356
I would def NOT house the pup with the boys in a kennel and be very cautious and observant of the boys behavior. I do put boys and girls in great big runs together , but I would not put my adolescent(17 months) in with my older aloof boy. It takes .02 seconds for it to go bad...
A little story , a looong time ago I had a puppy, that I bred, come back for training at about 11 months old, he's a puppy , right? Put him out with my 4 girls, (nobody in season) and an adult male, in a BIG yard. About 35 minutes later I heard a hell of a ruckus , and went out to find the WHOLE PACK taking jabs at the puppy. Apparently there was a scuffle with one and the pack mentality kicked in and they all attacked him.
I was fortunate with only one wound ,that required stitches ,on his side.
You should make your male dogs watch sesame street so they learn how to play nice with others.
Hmm every-time I've ever seen any grizzly old males introduced to a cute young female, they pretty much fail in love and spoil them terribly. Had a Big boy male Chessie fall pray to a little tan-furball earlier this year, the things he'd let her get away with, disgraceful. Might have to protect the boys from her. Just my experience with most "Any" breed ;).