I would imagine the parents probably got themselves in a right knicker-twist with their dd creating havoc and all the other passengers hating their existance. They needed Nanny 911! I worked in the US as a nanny (not on a show though) and American parenting tends to let the kids rule. This isn't everyone but most of the people I saw were helpless when faced with the fury of a toddler.
We have only had the chance to fly with dts once, when they were just under 2. Knowing plenty of flight attendants from my previous job as a passenger service agent I had lots of advice. Mainly, to stop their ears popping which causes the biggest problem, take their drink or juice in a sports cap bottle, make them drink it during take off and the force of their having to suck at it a little prevents their ears going. As already mentioned, make up their own backpack.
I also told them that if they didn't behave the captain would come and give them into trouble. Ended up they slept through both flights and I wish I could share the advice but I don't know why!