You can add your girlfriend as a "registered companion". She cannot be deleted in one year. (so make sure you don't leave her...lol!)

She shares the 24 total passes for the year with your parents.

No benefits for her, just the flight if you set her up as a registered companion. As soon as you get married then you change it to SPOUSE and she'll have unlimited flight and medical benefits.

And yes, you set up your account and set your parents & register companion. Have to wait 24hrs after initial activation to get the flight benefits.