Hello

I am planning to book 3 economy tickets (Q class) from ATH to IAH. It has a stopover in IST.

I have 143,000 miles available in my TMS (Turkish Miles & Smiles) account.

Do I need to buy any particular class tickets from Y, Q or H in Economy?

Will it be 45,000 miles to upgrade each ticket (both segments - anyway ATH-IST segment is only 1.5 hour duration)?

How do I find business class upgrade availability before booking my ticket as Turkish Airlines charges $100 cancellation fees per ticket for Q class (but if I book through Chase travel I get free cancellation up to 24 hours).

And can I upgrade all three tickets with miles from my account (as they don't have Turkish Miles & Smiles account) or does every individual needs to have create their own TMS (Turkish Miles & Smiles) account and have appropriate amount of miles in it?
Thanks