TK codeshare with AS - miles/luggage allowance?
 

TK's own website is offering flights to SEA, with the routing IST-ORD-SEA and ORD-SEA is operated by AS.

Obviously AS is not *A and I guess there would be no lounge access for Y as AS is not *A, what about miles and checked bags?

The international baggage allowance should apply to the connecting flight. Ultimately it will be tagged in IST even though you collect it at ORD and drop it off immediately after passing through customs.

Lounge is very unlikely - would AS even have one at ORD?

But you should earn TK miles on a TK flight code.

What about on the way back SEA with AS to ORD with TK? Would it be 2 bags? What about my *G status?

TK does not have a codeshare agreement with AS. Your ticket is just an interline ticket - therefore, no TK miles or lounge. The default baggage allowance applies all the way through IST-SEA - TK will grant +1 bag based on your elite status, but AS will not.

Any reason you are doing this connection rather than flying the TK IST-SEA nonstop? Changing terminals from the international terminal to domestic terminal in ORD is highly inconvenient, to put it lightly.

If you want miles and/or the extra bag allowance, you'll want a TK ticket that includes UA segments within the US, rather than AS.

What do you think the checked bag policy will be SEA-ORD-IST with AS from SEA-ORD?

TK doesn't fly to SEA daily, it seems that they reduced YVR down to once/twice a week to fly to SEA? For the dates I'm looking at the cheapest option is with AS, UA costs a lot more (to the extent that it's cheaper to book directly with UA and skip a night in IST both ways).