I won't be able to report back about the status benefits based upon my uncle's experience, as I booked him into First.

However, before I booked his travel, I called MP to get an understanding of how such award bookings work. Granted, you don't always get an agent who truly understands these things, but the agent I spoke with seemed experienced and knowledgeable.

She said, speaking as if I booked my uncle into Y, he would inherit my status in terms of Premier Access perks (check-in, E+, baggage, security, boarding) but would not be eligible for CPU. (I don't know how that compares to what SEA1K4EVR mentioned, about being eligible for CPU within one region.)

I thought I saw that in print somewhere on united.com but of course, now I can't find it. Or I was delusional