Thanks folks for the very helpful advice. I will most certainly be checking in 24 hours before my flight.
Mister Bates wasn't too far off as one my small travelers recently developed motion sickness and that's what's causing my concern. So there is a small chance that there could be a vomit moment. Nothing I can't handle but I'd rather not be crouching in the aisle leaning across two unlucky people trying to catch partially digested McNuggets with a gallon size Ziploc.
Neither of them kick seats though.
Does it make a difference that my flight is the last one of the day in terms of how full the plane might be?