Hey julia, big hugs for your BC, I remember you asking advice when you first got her, and I am so pleased to hear she's doing well!
My BC definitely sees kids as a threat, but he has never been around them in a day-to-day situ, and I doubt he will need to be. It sounds like Jasmine is just excitable, and as has been said in the excellent advice already, a little baffled about where she stnds-especially as your grandkids aren't around all the time. Make sure they are firm with her-it's important that there's no-one she can sneak to for more lenient treatment! Get them involved in her training, they will love it and she will also be less baffled!
Bear in mind that a lot of Collies nip kiddy heels, and make sure they are as calm as possible around her-no sudden movements or loud noises, which can be alarming for a dog, and especially a BC.
Let us know how it goes!