not really saying much that hasn't been said, but i personally would be giving little mack a little longer to recover completely (emotionally as well as physically) before the new puppy- and the risks of the new baby catching his parvo (although the titre test and breeder boarding is a great idea if she'd agree!)
i'm also not a fan of getting another dog just because a child wants one, but with what little i know of you and your family, I'm sure he is far more mature than the vast majority of young teenage boys...
saying that, i got kitty when i was 16, and missy (my mums) was about 7 months- while kitty was going through her pre-adolescent annoyance stage, missy hit her real stroppy teenage stage- that was the stuff of nightmares right there! won't new puppy and bryleigh (sorry if misspelled) be in the same boat when it comes time for growing up?
but it still comes down to the fact that (assuming the parvo issue can be overcome) do You and your Hubby want another dog- forgetting what your son Wants for a minute- will you both be willing to train the puppy If your son changes his mind, if he goes to uni and can't take him with, will you be able to continue to give them all their attention (emotionally as well as physically), and not fall out with anyone over it (i've known this happen
)?
how will he react if the puppy decides to follow his sister or parent around the house instead of him- my dads dog is like velcro to my sis, and even him at over 50 still gets a little upset about it- same as my grans dog who sticks to me!
like I say I don't know him, i don't really know you, so please don't think I'm implying anything (as typed things can come across badly and I'm terrible at proofing) but thinking a little more about it would be your best bet- and explain your concerns to the breeder, and see what she says- she isn't looking for a fast sale is she?!
its hard to resist those puppy eyes ain't it!?!