Hi, yeah, we are flying from Vancouver to IST with a layover in AMS.

I believe, like what ixs said, for transatlantic flights we are able to select the seats 90day before departure (the website stated this as well). I wasn't able to select the seats online even thought the seat map shows the seat as available. An error messgae just keep popping up saying the seat isn't available. I then called Delta to do it manualy for my return flight (for some reason, there wasn't any problem when selecting the seats for the flight from YVR to AMS). After it's done, I double check both Delta and KLM's site to make sure the seats are confirmed. Everything was fine until a bout a week later, my seat on the return flight was gone from the KLM site, but still showing on the Delta site. I guess will have to call KLM to check.