Originally Posted by gsorob
UA MP also cannot tell when, or if, we will be upgraded on the domestic segments. Furthermore, if the seats do become available, MP will call me to see if I still want to upgrade and if I don't not respond within 72 hrs we will not receive the upgrades.
If upgrade space is not available when you request an upgrade, you should be put on the waitlist. As upgrade seats open, they clear off the waitlist. If you are signed up for United Easy Update, when you clear you should receive a notice (so far, it has worked 100% for me, but some report it is hit or miss with them).
So I am not sure why MP would call you to ask if you still want them, unless they are expecting only one seat to open at a time (which is quite possible) and you need two. So they may want to see if you actually want the upgrade (if only one seat becomes available and you'd need to split the itinerary) or if you would rather pass and sit together in Economy Plus and then they can clear the next "single" on the waitlist.