Originally Posted by
stargold
That's not my understanding. For starters, given that SQ doesn't make longhaul R/F/J available to other Star partners, it would make it impossible to book Krisflyer Star Alliance awards involving SQ longhaul in premium classes.
I would find it much more likely that the OP got an agent who couldn't apply the correct pricing.
No if pokfur is correct the issue makes sense. When you book *A, you only have access to what *A partners have access to. So, SIN-FRA is unavailable and FRA-DFW is. If you book SQ, you can get access to SIN-FRA but not FRA-DFW because FRA-DFW is not SQ flight. Thus, the only way to get both is to book one SQ only fare from SIN-FRA and one partner fare from FRA-DFW. I imagine that if OP tried to price SIN-FRA in Y it would work (but probably won't want to).