Explain the situation. You already have a bonded pair and you want to add a third?

How old are the bunnies and are they spayed/neutered?

I think the first thing to consider is why you want three. I love my trio and they get on well, but it was such exhausting work. It look me just under two weeks (including a break of a few days, admittedly) but it was solid work. I marathon bonded them, so it was almost all day every day for much of the process. 

 there’s always a risk that bonding a trio won’t work or the existing pair will break up and you’ll end up with a new 2:1 rabbit grouping. Or, worse, three individual rabbits.

If you’ve already got the rabbit or are particularly determined, it’s useful to read about other people who have bonded three. I scoured the web and found a few different people, plus I watched lots of bonding videos.  I’ve linked to my journal and to my favourite blog about bonding but much of bonding is trial and error.

Quite lengthy and a bit dull, but from about page 2 you can read about I bonded my trio: The Adventures of George, Charlie and Albus.

I was largely inspired by TanLover’s blog, which I advise you start on how she bonded three siblings but (if you read it at all) make sure you read the additional buns she bonded into their fluffle. The non-sibling bondings will be much more informative if you’re bonding and unknown bun or have a difficult bond. I recommend it to most people with questions as I think it’s very good: thebunnychick