T1 is one terminal. MFC and NSC are 2 concourses of it. This  follows the name, obviously. 
2. `site=terminal` is invalid. What "terminal"? `aeroway=terminal` should be used Don't use `=site` either when `=multipolygon` is fine. Then it has the meaning as T1 being a `=terminal` covering all of these concourses. It is inconsistent to have some concourses being `=terminal` . and others simply a `building:part=` . This doesn't follow how they are named as T1 either. Different `building=` doesn't matter. 