the pairs of 3 seats note the rear row is an exit row as the tray tables are stored in the armrests - they may come from door 3L/R
good point on the exit row (which one is to be determined), isn't row 9 (toddlers location if seated) around an exit? from the location of the outer tray table in the arm rest aren't these from the right side of the plane (D, E, F)?
The structure under the two pairs of three that supports them is pretty bulky and how that came detached (not just the chairs by themselves) seems suspicious.