I have had this happed to me before on a KLM flight AMS-MEM. I was in business, two parents were in business, and thier kids in coach. The kids spent the whole flight running back and forth to their parents, running around the business class cabin, making noise, and generally ticking people off. Someone must have said somthing, as one of the FA's told the kids to go back to coach and never come back (the parents sure weren't doing anything). They listened, and we had a peaceful flight after that.