[targonrotts]

the hardest part you will have especially if unexperienced is keeping the intact male away from the female when she is in full heat.
maybe in the first heat he may not be so whinny or destructive(i still would not trust him alone near her and for safety of unwanted pregnancy, keep them apart from first sign of heat until at least 3-4 weeks).
but by the time he is aware of what is going on, he may be loud, not eat, try to get out of crate/room/jump fence.

as to the older one, depends on dog's character. male may be obnoxious and older female corrects him if he tries it on her. younger female and older female may engage in rough play/fight/or do nothing. play it by ear and be ready to separate if need be.

as to the vet comment and akc comment:
akc papers any dogs that came from akc stock and have been registered. they don't look at quality. just paperwork properly filed. vets are well meaning, but specialize more in dog health, not breeding or showing(unless they do it themselves). i work with vets, i know. some well meaning think it is ok to breed in second heat, but in our breed, that is too young and not old enough to see what is going on with hips, elbows, heart,eyes,ect.
i am not dictating you or telling you what to do. just passing on experienced info.
breeding does take time, money,effort, and research to do it as best as you can. and good homes are hard to find.

good luck with your dogs and hope you stick around. you will get all sorts of replies, but with an open mind, you learn alot.even us older timers do!