I was concerned about this due to flying with the misses and baby next year to SJC (787), so once we got our reward seats, I tried a a cash booking for 7 people to take it to 9 seats but it wouldn't let me, could only book another 6 seats in the cabin. It's definately route dependant where they allow overbooking in F I think. I'm going to take a stab in the dark that it's 747/777/a380 routes more than 787 routes due to the 14 seats? Would be interested to know if any downgrades have happened on 787 routes?