> I’m unclear as to whether I can spend HSA money on the family prescriptions and office visits

Virtually any healthcare spending is a qualified expense for HSA purposes. It's any medical expense that could be counted towards the medical expense deduction on your tax return, for you, your spouse, or any dependents, regardless of whether they're enrolled in the HDHP. It's pretty easy to spend HSA money. Less so to contribute it if you're trying to mix-and-match coverage.