We could have a bit of a buffer from CHQ to a bigger city, but I'm a little worried if it's a day and something goes wrong from CHQ, we might miss our flight home. We could make it 2 days buffer just in case, but I'd have to talk to the others in the group to see how they feel about it. Originally we actually wanted to do London, France, Greece then Italy. We found flights for this that would work with SQ (CNS-LHR, FCO-BNE). Then we'd be able to fly from France to Crete, spend time there, and head back to Italy before heading back from FCO later. This would give us a nice buffer, but going from France to Crete and back to Italy adds an extra ticket cost which ends up adding quite a bit to the ticket price. That's why we decided to do London, France, Italy then Crete; the main ticket component (CNS-LHR, CHQ-BNE) would be about the same price as the old SQ itinerary we were looking at (CNS-LHR, FCO-BNE) but because we'd only need a one way ticket from FCO-CHQ, it ends up being quite a bit cheaper. Then we'd make our way down to FCO and get a single one way ticket from FCO to Crete, relax and do Crete related stuff for a few days and then head home directly.

Also for the second part, I'm always up for learning and stuff, so no need to apologise for asking your question! We have travelled as a family before, but all within AU. We've done interstate trips together before, but nothing to this scale. We've been looking into things and reading up on how it all works and everything we need to do, so we've been getting some ideas already which is good, but it's definitely going to be new stuff for us to learn, but thankfully we have 8 months before we leave to learn everything we can about it, so at least we got that going for us! Also what's special about flying in Y? Isn't that the highest booking class? I thought the itinerary I posted has us flying in T, not Y? Either way, we'd be down for some optimisations, especially if it brings us to a lower booking class (which would be cheaper too from my understanding?) We have to leave from CNS but I suppose we could land back in CNS and fly to BNE ourselves afterwards if that makes it easier? How would we go about repositioning within EU better though? If we went with the SQ flights we were looking at originally (CNS-LHR, FCO-BNE) that would be a lot less connections, since it'd just be AU-SIN-EU in both directions, but we'd have to pay more to leave out of CHQ? I guess they each have their pros and cons, unless there's some magic stuff I'm missing in ITA matrix that might help with it?