And this does happen. Once we had pre-boarding because our one year old was handicapped. Because my husband needed to put his car seat in place while I took care of our son. The whole family (me, DH and 3 sons) had to line up to pre-board. Actually we checked with the agent at the gate and she understood completely until.....B26 and B27 started freaking out. They started screaming that our older kids could hold the baby and the bags. And I should go to the back of the line. They created such a scene the gate agent was unable to control them. She asked if I'd mind taking my place in line. No problem, I was A4. They got worse. They wanted me in back of the line. I did just for the sake of peace (I was not worried about where I was going to sit). Unfortunately, the baby had a fit when he got on the plane without me and broke out of his brace. The older kids were scared because they could not control him. Take off was delayed by a couple of minutes because we had to get his brace back on and it took time to get him situated in the seat (hence the pre-boarding) and he cried in pain the whole flight home. I hope B26 and B27 were satisfied.

So, yes I guess OP should be prepared for B26 and B27.