Why is she being a major pain!!??

Female dogs tend to be a lot more bossy than males, and often end up being the dominant pup. I see it even with Yogi and Lady, even though in Lady's case, she's pretty submissive. Still, she's always knocking Yogi out of the way, things like that.

You might have to just let them work it out. And it's not so bad. Here, Yogi seems perfectly happy to let Lady be the boss, as he doesn't handle responsibility well . Just make sure it doesn't cross the line and their rassling stays relatively benign.

Sadie will be like that with Max, for no reason at all she would go into attack mode on Max, I used to try to break them up when it sounded like it was getting too rough, I was afraid one would get hurt. My brother suggested I just let them go for a bit and see what happens. I did and they went on like that sounding pretty vicious but then just broke away from each other and it was over. I couldn't really tell if there was a winner or not they would just break apart and that would be the end of it. Since that time I have just let them go and it never last too long before they break apart and just walk away from each other. It was worse when I tried to break it up, now I let them settle it themselves and it's a lot less stressful for them & me.

I had to artificially establish Lightning as above Stomps, because Stomps wouldn't stop trying to assert himself. The fights he would instigate got very, very ugly. I no longer let either of them sleep in my bed, and I only let Lightning sit in my lap. I feed Lightning first, and I feed them in separate rooms. I've kept to this for about 7 years now, and we've only had one major fight in that time. I guess it's up to you to decide whether they will establish a pecking order and things will settle down. I've known pairs that never quit going after each other (it's usually one that's the instigator). And obviously others have had different experiences. Good luck.

You may have to let the dogs 'duke it out', BUT because of the size difference here, I'd keep a very close eye on things. I've no doubt that your Jack isn't going to back down, being a terrier, but he could be biting off more than he can chew here.

By the way, DH says that bitches rule -- in every species !