You guys should not have any complaints with your "little ones"...
Argentina kids are all future soccer champions, Maradona class...
Especially if you are from Manchester United, they will take care of the back of your seat.
After all, Buenos Aires to Madrid is a mere 11 hrs long flight.
And if you do not like Argentina, take a Varig flight with Brazilian kids.
xxx
Happy contrails - bang bang bang...
P.S.
Maybe put the kids in a kennel, maybe, with checked baggage...?