Thank you both for your comments, the multiple PNRs on different airlines and the SQ issue certainly helps in my understanding.

As a non-UGS 1K, and being on an award ticket, I think I will just be happy with my current itin. The risk of something going wrong with SQ, and losing the confirmed seats are just a bit too risky for me (actually for Mrs. Jet2K) .

Three of us are on all the same flights, and on a fairly complicated itin:
- 9 segments
- 3 carriers
- 2 deliberate overnight connections in SIN
- 1 long day connecting in HKG
- 19K+ of BIS award miles
- Final destination of Bali, lengthy stopover in TPE
- 2 separate PNRs (#1 for one passenger in F, #2 for two passegner in J)

If something goes wrong in splitting the PNR, I am very doubtful that we can re-secure space on the flights, currently several of the segments does not have any award availability within a several-day span. If I am on a revenue ticket, I probably would go ahead and request separating the PNR as a learning experience on what could go wrong, and more importantly, on how each of the airlines act to resolve the issue.