You are never going to save money by buying an Economy ticket and then buying all of the miles needed for Business Class upgrades.

Business Class upgrades require inventory in J class, which is TK's cheapest Business Class fare. If that is available --> you should just pay cash for that fare.

Add the stopover - which means that you pay 2 upgrade fees instead of 1 and are also far less likely to find upgrade availability - and the need for 3 tickets, and you're aiming for something that the TK experts around here would struggle with.


You also spend the same number of miles for an upgrade as you would spend for an award ticket. So keep it relatively simple and look for award space in Business Class for 3 people. If you find it, then you can think about acquiring TK miles, Aeroplan points, Lifemiles, etc. to book the award flights.