Greetings. Star Alliance Gold member here traveling to Australia on United and then have 3 Virgin Australia Flights on different days while I visit your lovely country for the third time in Januaary before the new rules. Last time I flew Quantas in country which has carry on requirements like United, at least they did in 2015.

First off, let me be clear, I don't want to game the system. I am trying to figure out how to be compliant. I already know I need a new Carry on that meets the 56x36x23cm. Looking at the Travelpro Max lite 20" which is fully compliant. On their web site they say personal items are essentially hand carry (laptop on its own, etc). That would not be a backpack. Some have said with this size bag, I also can bring a backpack as long as it fits under the seat. Since it doesnt say that on thier web paage, thinking that isn't the case.

Is it the two bag item of 48x34x23cm with each being 7kg's that allows a backpack in those dimensions and can you bring two bags that size? My backpack I carry my laptop in is compliant with that.

My carryon and backpack are compliant on United together so I would fly with those two onboard and a half empty checked bag. I get a free checked bag per my reservaation. Then when I get to Australia, empty most of my carryon into the checked bag and put my backpack in my carryon. That would meet the size requirements, but then concerned about the 7kg weight limit. That would be hard with the carryon. I would have to weigh this approach to see if it is feasible.

or with the weight concern, I can have two backpack sized bags 48x34x23cm each with a weight limit of 7kg's? so I could carry 15 kg's if weight is the driver in two bags that are smaller. Do I understand that correctly, 2 smaller bags for a total of 15kg?

If I weigh my compliant sized carryon and its 10 kg vs 7kg, is there an option to pay for a higher allowance or do I need to make sure it is under 7kg?

Again, only wanting to make sure I understand how to be compliant.