Interesting
Called back to book the Mother in-law's seat and the guy
1. Instantly looked up her reservation based on the UA ticket# (previous person took 5 minutes)
2. Said row 11 was wide open and put her there
3. Put her in 42G
Was so shocked, I forgot to inquire about changing the rest of family. So I called back and...
Got ANOTHER person who said that while she could put us there, we were subject to being moved if a passenger with a bassinet needed the seat (understood).
Anyway, very inconsistent experiences.