Thanks for your replies. I checked each airline's website and unfortunately for economy class it's basically one carry on per person with the exception of Air New Zealand you can also take a slim laptop bag - the Zucca backpack is anything but slim. Should we risk it? Worst case scenario we check in the backpack right? We're emigrating on one way tickets, maybe they'll give us some leeway? Egyptair is usually very good about these things but not sure about Air China and Air New Zealand - has anyone tried them, are they as strict as Lufthansa about these things?