It shouldn’t change the bond that is already there between the two females. Not sure if the third is male or not, but I know it’s doable. Some personalities work best or are easier to bond than others. You could always ask to try something temporary to see if it works. I know that I have seen articles online for different bonding situations, including 3 bunnies involved. All bunny bonding info available online is how I bonded my 2.
Just make sure that all of the rabbits are spayed/neutered, if they’re not. I’m guessing they are, but just to make sure! Is one female more dominate than the other?
Sometimes, adding a personality to the mix will make one bun more dominant and I’ve also heard that it’s not unusual to see humping (displays of dominance) in more than one.
The only way to be sure is to try to see if it works. What is often hard with the temporary length that’s allowed is that some buns can take months to bond. Mine took about a month. So don’t feel defeated if this is the case!