Join Date: Jul 2003
Location: CGK
Programs: SQ TPP30, CX DM, DL P, FB P, AA G, GA CB, WOH LGLOB, HH D, MB G, Hertz P
Posts: 2,887
My guess is best to request nicely at check-in if the flight load is full or not, and whether there's a chance that the agent can block off an empty row for you. Being *G should help (a bit).
The authority lies in the SQ airport office I think.