If I go to
At Hilton Grand Vacations, we believe life is incomplete without vacations. Learn how you can see the world from the comfort of our timeshare resorts.
www.hiltongrandvacations.com
and click on Login, I get several choices, one of which is
"Vacation Package Holder"
I do have a login there (we have had these in the past), but don't recall how I set it up. When logged in there, could see the details of my package. Not sure if I could see availability, though.
Cheers.