US and UK Discounts

[PoohsHunnyBee]

We are toying with the idea of an extended family vacation in the future and hope that someone here can offer some insight. My family and my parents live in the US while my sister and bil live in the UK. Tickets, rates, and discounts seem to vary greatly. So, how does this work if everyone wants the same type of tickets and discount? Can we book everyone with US tickets and discount? Can sis and bil book everyone with UK ultimate tickets and discount?

If there's a better board to post this on, or somewhere this has been answered before, please let me know and thanks in advance!