Get her spayed, Nan, that temper, screw tail and fucked up lower jaw are all genetic. You can't really breed it out, you just put more bad genes into the pool. You could breed her to the nicest male on the planet and the odds are up to 50% of those pups will come out with her disposition or with messed up mouths or spines and the ones that don't come out messed up still carry genes to give it to their offspring (which could be how you started out with a nice looking pup that went off the rails).THIS x2
I paid a ridiculous amount for my frenchie because she was almost an investment, she was going to be for show and breeding, she is AKC bred, came from champs in Canada, Mexico, US and Europe, we saw both parents in the home, both gorgeous, when I first had her she was the PERFECT pup, all the correct and desired frenchie traits were present, perfectly round bat ears, no white in the eyes when looking forward, short tail, perfect teeth, awesome posture, compact body, easy going temper. Eyes and ears are still great, upon growing the tail turned out to be a screw tail which she rarely wags, once she teethed her bottom row came completely crooked, her body got leaner almost athletic like a boston terrier, her temper is horrible, she wants to kill everything that moves and while playing she over excites and nips, she is unshowable now. I've even hesitated breeding her despite the fact I haven't got my"return" on what I paid for her, but the thought of how she might be as a mom and how her puppies will grow to be have me on the fence.
Unless you are going to show them you wont really need full blown champ blood line AKC dogs, aim for CKC/NKC if you want the security of controlled lineage since CKC and NKC don't really give a fuck about money/shows/traits that much and they inbreed faaaaar less.
And even if she is a good mother if she's unpredictable now you've got a good chance she's going to completely flip her shit as she gets closer to whelping, you might not be able to get your hands on the pups without a battle. Never seen a dog savage it's own litter but I'm sure it happens (seen ferrets do it a lot, nasty, talk about eating your young).
I get the investment thing being a bitter pill but any time you deal with animals on a business level there's a risk.