You might try spraying the terriers back with bitter apple or something PROVIDING the skin itself isn't broken. Maybe if she gets a mouthful of nasty taste she'll find something else to grab. Is the puppy a new addition? Sometimes dogs act odd when you bring a new one in if it's not done properly. Make sure they have plenty of time and space away from one another as well.
Be sure to help her establish her dominance over the terrier, by petting and feeding her first...and she may calm down. Her mounting of you is likely dominance behaviour as she may be unsure of her place now the the new dog is there. If she knows the "OFF" command use it...and back it up by a spray bottle with water in it or water mixed with vinegar. If she likes being sprayed...a loud noise like a foot stamp or hand clap or shake can might work....it has to be done RIGHT WHEN she starts the behaviour tho and say OFF firmly. She might catch on that you won't tolerate it. Everyone in the household should react the same.
If she won't cease...say NO, OFF...then confine her to a crate or put her in a time out somehow. You can also do the opposite and tie her to you with a leash while you go about your day at home...she will HAVE to follow you and move when you move...etc. After a few days of this most dogs cease any clingy or uber dominant behaviours....only do it a half hour at a time tho.
I think she just may be confused about her place right now. The Jack may also be maturing sexually and sending her some signals as well...further making her wonder about her place.
Good Luck!
RWB

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