As suggested above, if business class is sold out and every other passenger has preselected seats, your party could be spread all over the cabin. It just depends where those last three available seats are. Unfortunately QR are not going to move people who have preselected seats to allow a party to sit together when that party had chosen not to pay for seats or a seat-choice inclusive ticket. Imagine how you might feel if you got booted out of your chosen / paid for seat under those circumstances.

There are a bunch of economy fare buckets that do not include seat selection either. As with business tickets, the inclusions and omissions are clearly indicated for each fare level when you chose which you wish to buy. QR are far from unique with this type of fare structure.

So you might be lucky at check-in and there are three seats close to each other that can be allocated to your party, or you might not. The only way to guarantee where you'll be sitting, having chosen the ticket type you have, is to pay to select seats now. That might still be cheaper than buying the seat-choice inclusive ticket may have been originally. Or alternatively, try to find some qualifying oneworld status for one of your party between now and departure, which also allow you to choose seats for free.

And bear in mind also that if it is a Qsuiites aircraft, and you choose or were allocated three adjacent seats along the window side of either aisle, you would all be sitting in individual "boxes" anyway, and be unable to talk with each other without standing up.