i totally agree with apaddyinuk!
If the family got money to spend on the little ones,they are at liberty to do so! When they are buying tickets ,it would be hard for the tickets agents to ask if they have "screaming kids" nor do they have a section on the online ticket purchase that one may "tick" reading "Do you have screaming kids?"................
That was just an unfortunate flight, Qatar Airways cannot be blamed for it!!!
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flyoneday