Yup, she's proabably got some herding dog in her and her puppy attitude is coming out.
I'd get her enrolled into a puppy class as soon as you can. In the meantime I wouldn't leave her around the kids unsupervised. Classes will teach her (and you & the family) some much needed manners & basic commands. They will teach you how to heal, not pull on the leash, not to nip. In the meantime try to redirect the behavior. Teach her to carry a ball or toy on her walks.

Also make sure that she knows that this behavior is not acceptable, NEVER. You will need to speak to everyone who handles her and is around her to make sure everyone is consitent with each other & persistant too. When she does nip at the ankles make sure everyone uses the same command, like a firn NO or NO BITE, and remember to PRAISE when she lets go or stops the bad behavior. Then RIGHT AWAY offer her something she can chew on, a toy & praise again as soon as she takes the toy that you offer her.

Good luck.