Thanks for the responses all...am more interested in the 'long' answer though... this is now in the hands of the relevant ombudsman (Airline Customer Advocate) as I cannot let this rest due to the impact this has had on my family (very long story). Besides, worst case scenario for weight calculations would have incorporated the higher end of the weight range for each of the other passengers already checked in for the flight, so there would have been plenty of 'slack' already in the total calculated weight to account for my wife and 4 kids.

Thanks for the responses... to put this simply, there were 5 of us in total who were denied the flight. Passenger A - 70kgs, Passenger B - 55kgs, Passenger C - 50kgs, Passenger D - 50kgs, Passenger E - 30kgs. Total 'carry on baggage' weight - 40kgs. Flight was Brisbane to Melbourne (2hrs 10mins). Aircraft type Airbus A320. I guess what i'm trying to determine is: Would there have been a significant alteration to the weight and balance calculations had these 5 passengers been permitted to fly?

Thanks for the responses... to put this simply, there were 5 of us in total who were denied the flight.