Lifetime bronze QFF member here. Booking separately had worked for me on one occasion the other it failed. These were J seats.
I would suggest using a tool like ExpertFlyer to check how many award seats are available. The instance where it worked for me, it was most likely 2+seats available however they only wanted to give one per Bronze member.
The time it didn’t work required me to be on the phone for multiple hours, making a complaint which after many calls I got put onto an Australian operator that open up a seat to shut me up. This was back when I didn’t understand how availability worked and I was just booking on what I saw when logging in on two different accounts. I don’t recommend going down the low odds verbal jujitsu roroute.