If you have enough kids it's kinda a sink or swim moment: you learn to tune it out or go crazy. We have twin 2 year olds and a 5 year old. There's been periods of time where there's crying (by at least one of them) for most of the day. When you're 1 on 3 at these sorts of ages it's inevitable. When 1 starts crying in the car and the other 2 start crying because the crying is too loud, there's not much you can do but laugh about it.

Take solace in the fact that kids cry over ridiculous stuff. For 20 minutes. Because, for example, you peeled their orange for them.