On the web site for SIN-IAH and IAH-SIN (9Nov /19 Nov), it shows the MAN stop both ways but still includes the Moscow route as well for the return. But it doesn't come up with anything for MAN-IAH-MAN as Viscount702 says.
Yup - not updated in the GDS yet.
Both flights loaded at the moment - the old SQ327 and the new SQ51 - but both zeroed out in discount economy.
1 MAN SIN 1135#0820 SQ 51 F4 A3 Z4 C4 J0 U0 D0 Y9 B0 E0#77WC*E
2 MAN1SIN 0845#0740 SQ 327 F0 AC Z0 C0 J0 U0 D0 S0 T0 P0#77WC*E
Same for Houston:
1 MAN IAH 1015 1535 SQ 52 F4 A1 Z4 C0 J0 U0 D0 Y9 B9 E0 M0C*E
H0 W0 Q0 N0 VC G0 L0 K0