Got my SQ PNR from UA and used the SQ mobile site to check my reservation.
Was able to change my seats to move further away from the other person in the cabin.
[Edit: Also able to find the reservation on regular site, but changing seats doesn't work that well. Funny thing is, the "other person" shown on the mobile site isn't shown on the regular site.]
One somewhat interesting observation:
According to the UA booking, both SFO-HKG-SIN and SIN-MEL are on the
773ER, but according to the SQ site, SIN-MEL is on a
773 ver. 2.
According to SeatGuru, both aircraft F class seats are the same size (71" long, 35" wide) and 8 F seats (and the SQ site confirms the cabin layout), unlike the
773 ver. 1 that is "only" 64" x 21" and has 18 seats.
According to UA, the return trip is 25 hr 15 min, but SQ's site states 26 hr 15 min. Same departure and arrival times on both sites...