Singapore Airlines KrisFlyer - Yet another noob question ... seat availability

So how does this work exactly? I've got a work trip coming up in 2.5 weeks. Got myself confirmed on SQ997 + SQ231 for NRT-SIN-SYD. Currently I'm waitlisted on SQ221, which I'd really prefer.

So playing around with KVS and checking Sabre I find this (looking for SIN-SYD):

[KVS Availability Tool - Sabre: ITN/AXP] (http://www.flyertalk.com/forum/showthread.php?t=319244)
SIN Singapore Changi SG [WSSS]
SYD Sydney Kingsford Smith NS AU [YSSY]
SUN 16 Oct 2005

Carrier Flight From Depart To Arrive A/C St Availability
--------- ------ ---- --------- ---- --------- ---- -- -----------------------------------------
SQ 221 SIN 20:30 SYD 05:50 +1 744 0 F4 P4 A4 Z4 C4 J4 D0 Y9 B9 E0 M0 H0 W0 Q0


However, I also get this when checking for availability NRT-SYD:

[KVS Availability Tool - Sabre: ITN/AXP] (http://www.flyertalk.com/forum/showthread.php?t=319244)
NRT Tokyo Narita JP [RJAA]
SYD Sydney Kingsford Smith NS AU [YSSY]
SUN 16 Oct 2005

Carrier Flight From Depart To Arrive A/C St Availability
--------- ------ ---- --------- ---- --------- ---- -- -----------------------------------------
SQ 997 NRT 11:30 SIN 17:30 744 0 F2 P2 A2 Z0 C0 J0 D0 S9 Y9 E0 B0 M0 W0 Q0
-> SQ 221 SIN 20:30 SYD 05:50 +1 744 0 F2 P2 A2 Z0 C0 J0 D0 Y9 B0 E0 M0 H0 W0 Q0


What's the deal? Checking for a simple SIN-SYD shows that they're selling at least 4 seats in C but when turned into an NRT-SIN-SYD trip there's 0 seats.

Should I just tell my TA to rebook this as two separate bookings?

Should I just tell my TA to rebook this as two separate bookings?

Yes. It´s showing zero availability as a married sector 997/221; just book them separately and it should be fine. I never like booking married segments as you´ll have to cancel them BOTH if you want to make changes, but sometimes inventory works the other way, where you´d have availability on married segments but none when done separately.

What's the deal?The answer to that question can be found in the KVS Tool FAQ under "Segment Marriage Logic":