I'm trying to help a friend book his family on United. They have points with Chase UR and will transfer over to United.

My question is about searching for 6 tix...sometimes won't the site show different availability depending on the number of pax you search for?

If can find say 3 award tix, how do I know they're not the last 3 seats on the flight? Am I better booking this via the phone? I wouldn't want to get 3 on the plane and then find out the remaining 3 couldn't buy a ticket. Also, if I am able to book 3, is it possible that more will show up for award tickets (say 1), but 4 wouldn't show up on one search?

Thanks so much!!