Originally Posted by IAH-OIL-TRASH

It's the only way to find PZ. UA doesn't release PZ early, and if they do, the existing waitlist is likely to gobble them up. There are occasionally very brief times when PZ is allocated before waitlist is run when PZ and very lucky traveler can grab it. Unless you can find PZ at booking (very unlikely), your mother would go on waitlist with your PPs at her status. Buying PremiumPlus would boost her chances, but still a tough route for upgrades. If she's in PremPlus and fails, she's still in a far better seat than economy.