I am new to earning and redeeming Krisflyer miles (or any miles in general), so apologies in advance if this is a stupid question.

My partner and I both have our own Krisflyer accounts, with our kids linked to mine.
We have a cash paid booking SIN - WLG return in March next year booked in Economy Standard (W) which I am hoping to upgrade to Business Class using our points. However I know we can't pool points so I'm unsure how and if it will work:

2 adults, 1 child - all in one booking
Husband - has enough points to upgrade 2 pax to business return
Myself - has enough points to upgrade 1 pax to business return

As it's all under one booking, can we only use the points of one of us to upgrade?

If the above is possible and we are able to upgrade, I then noticed when looking online that it says the flights are unavailable to upgrade - I booked in the correct fare class to allow upgrades so my assumption is that there are no business class seats left on my flight? Would I then need to perhaps change flights to one where there is availability?

** Edit to add: I also just got Krisflyer Elite Gold Status, no idea if it makes any difference to my above scenario though **

Thanks in advance!