It looks like we-re *both* correct. (Though I'm more so.) According to this Coverage for Pre-Existing Conditions:
Being sick won't keep you from getting coverage
Your insurance company can't turn you down or charge you more because of your pre-existing health or medical condition like asthma, back pain, diabetes, or cancer. Once you have insurance, they can't refuse to cover treatment for your pre-existing condition.
This is true even if you’ve been turned down or refused coverage due to a pre-existing condition in the past.
One exception: Grandfathered plans
The only exception to the pre-existing coverage rule is for grandfathered individual health insurance plans -- the kind you buy yourself, not through an employer. They don’t have to cover pre-existing conditions.
If you have one of these plans you can switch to a Marketplace plan that covers pre-existing conditions.
So your relative, who has worked in a doctor's office for many years and "damn well knows what she's talking about", should know all this and tell patients with grand-fathered insurance plans to switch to a Marketplace plan that does.