Can I set up a 2nd (non-cellular) watch from my phone?

I've got a spare non-cellular series 3 watch that I want to give to my kids for running practice. My wife and I both have iPhones and paired watches, and I don't want the kids' watch to be getting our messages or adding workout records into our accounts. The series 3 won't need an internet connection or anything more than showing distance/time. Is this possible without pairing it to a third iPhone and without it becoming entangled with my data?

I've seen other questions here that seem to be focused on one person owning two watches, or specify how it works with cellular watches but they don't quite cover my use-case.