This gets asked for various partner combinations all the time and the answer is always the same: save your boarding card and request missing mileage credit after the flight. It won't post automatically but when you request missing credit it generally comes through fine, regardless of how we may want to parse the fine print on the mileage plan website.

Case in point: I got missing mile credit last week for a DL flight operated by AF and an AF flight operated by TAROM(!)

Neil