I'm having a little trouble understanding exactly, but UA will offer Farelock on some itins and not on others. They may also offer a 3 day farelock but not a 7 day on some - I've seen it before, though not often.

Some will suggest, and I've noticed in the past, that farelock doesn't seem to be offered if it is over a period where the fare would be unavailable at the end due to advance purchase requirements. But I bought one a week and a half ago (see my post above) where it offered it to me even though it did go over the advance purchase deadline, YMMV, I guess.

And in reference to my Farelock experience which I did promise I would follow up on - it did let me keep both, even with them both having the exact same return. I bought the ticket I wanted about 24 hours prior to its expiration, and let the other one cancel itself out.