MilleMiglia also has the option to purchase miles (25 Euros/1000), which I suppose you could do from your tablet or laptop at the airport. However, from reading the MilleMiglia website info, it appears that 25% of an award must be 'earned' rather than purchased or transferred miles. Amex Membership Rewards transferred to MilleMiglia show up as 'earned', so they can count as the earned portion. So one way to play this would be to seed your MilleMiglia account with 5,000 membership miles, and then top it off at the airport with either purchased miles or add'l membership miles if an upgrade is available. (I moved enough into my MilleMiglia account before going to the airport, because I don't know how fast Membership Miles transfer and hit an account. With a little more forethought, I could have tested that out with a couple of thousand points.)