From my one of my current policies:
"Persons or classes of persons, whose liability is covered
The insured [me] and any person whose driving is covered except any person in the motor trade who is driving with the policyholder's consent for the purposes necessitated by the overhaul, upkeep and/or repair of the insured vehicle.
Vehicles or classes of vehicles, the use of which is covered 08-XX-123456 [my car's reg. no.]
The policyholder, if they have a full EU licence, may also drive, with the permission of the owner, any Private Motor Car subject to the T&C's of the policy.
Drivers or classes of drivers whose driving is covered
Named Drivers mathepac
Named Drivers Only."
I dropped Open Driving from my policy some years ago, so OP's 25 year-old female relative is not covered on this policy to drive my car, even with my permission.