[mothered]

Are you referring to Amazon FBA?

If so, It will not affect any method. They (Amazon) simply pick, pack and dispatch goods on behalf of the seller, and also take care of returns/refunds.

I'm guessing that means FBA if it's fullfilled by amazon but sold by someone else right.

Yes, that's correct.

Amazon handles everything on behalf of the seller, Inclusive of transactions. It's as though you're purchasing directly from Amazon.