A similar question has come up before here. I called my car insurance carrier to see what they had to say about it. The agent’s response was that as long as the owner of the car had insurance on the car, it didn’t matter who was driving in the case of an accident.
Last year, Mom relinquished her driver’s license when her eyesight got so bad that she knew she would be a risk behind the wheel. She hired a service that would take her on errands once a week. They always took Mom’s car. While out on an errand, they were in a minor accident. Mom’s insurance company covered the cost of repairing the damages, even though this unrelated woman was driving it. (She uses a different carrier than I do.)
The only scenario I know where other possible drivers need to be added to the insurance policy is during a transaction for a rental car. It’s worth a call to your insurance carrier to find out what their policy is.