re: Didn't realize doctors weren't allowed to treat family members

There's no law or rule against treating family members, but in general its discouraged.

Sending in the occasional script for some antibiotics, steroids, drops etc. Is fairly common, although some states are more restrictive than others even for those prescriptions. You're supposed to have a written medical record even for those instances, but most people don't.

Otherwise longitudinal/long term care is allowed with written medical records, but for the sake of trust and openness, usually not recommended that your relative is the treating provider. Patients have a hard enough time disclosing certain symptoms to doctors, you can imagine that someone may have trouble telling their spouse, cousin, or whoever about any sexual dysfunction concerns, bleeding issues, breast masses, etc. And those areas may go unexamined for the same reasons.