I know SQ always had a good availibility to their own Frequentflyers and once I really needed to have one additional ticket since I got only 2Award tickets in Business via Lufthansa MilesandMore.
Therefore i had to transfer points from certain hotel programs just to get the additional Award booked

But I also have to admit, I either was lucky or not. But most of the times I was able to get Awards in Business class via Lufthansa Miles and More for SQ flights for 2-3persons.
On the other hand, i always book at least 7-8month in advance maybe thats why i always was able to catch some seats.
Recent booking for August from Muc-Sin with our preferred Dates.
For the 3rd. Person i had to pay for the ticket, since these were the only 2 available seats that time.