Do you normally backshift a verb in the that-clause of 'make sure' when the 'make' is 'made,' 'could make,' 'would make,' etc.?
Please take a look at the examples below. Are my thoughts on the right track?
A man is asking his travel agent to get seats next to each other's for him and his wife on a plane.
 If you could please make sure we (sat/ sit) together, I'd appreciate it. My thought: Either is fine. You could backshift 'sit,' but you don't have to.
A man asked his travel agent to arrange consecutive seats on a plane for him and his wife, and they did.
 They made sure we (sat/ sit) together. My thought: If sitting has not yet happened, you can say either, but if it did, you only can say 'sat.'
 They made sure we (would/ will) sit together.
My thought: If sitting has not yet happened, you can say either, but if it did, you only can say 'would.'