Jeebus. Certain agents that I've met hate working certain flights (MCO being the main one, SAN, MIA, and LAX during vacation season) owing to large families. I remember this happening to me several years ago when I was traveling with my two sons to California - one was about 12 and the other 10 at the time. We busted out connection in CLT and got put on another flight which was filled to the gills in coach but moderately empty in first. I had opted not to upgrade owing to the fact that I could only upgrade one child with ease - there were plenty of seats which was frustrating....
Agent tried to shuffle us around but was having issues. Then she noted that I was plat, and asked why I hadn't asked to upgrade. I mentioned that there were three of us and I couldn't upgrade two companions. Agent furrowed her brow, and asked if I still wanted to use some of my stickers. I mentioned yes. She instantly upgraded me and one son with stickers and comped the second upgrade companion. Probably the only time where I've been able to upgrade both kids with only one elite on hand.