Bonding rabbits together

Stress Bonding
Stress bonding entails creating a situation for the rabbits where they will cuddle together in comfort against the frightful environment and consequently learn that being friends is not that bad. Like any other type of bonding, your mileage may vary.

User neanderthalman from Reddit gives one method of stress bonding: "We put a little warm water in the tub, then after a few minutes, put down a towel to sit on. Forces them to sit together, as they hate the water more than they hate each other. Then after a few more minutes, drain the tub. Then towel dry. We then put them in a cage together so that they aren't separated and 'unbond'. Generally no issues beyond a few squabbles and nips here and there."

Bunny Dating
Many people do not realize that the majority of rabbit rescues offer "bunny dating" services. The rabbit experts examine the interactions between potential partners to find the best match, as opposed to just trying to bond two rabbits without knowing their preferences. Some agencies offer "speed dating", while others will let you bring your bunny to the shelter multiple times or even overnight. Having the rescue as a resource when the two bonding candidates are having issues at home can make the process much, much easier. In order to participate, your rabbit must be spayed or neutered.

Bonding Multiple Rabbits
User neanderthalman from Reddit has had success for a trio using his stress bonding method in the bathtub from the section above. He recommends placing the most aggressive rabbits in the bathtub first.

The following links contain more information about bonding multiple rabbits.
 * Reddit, /r/rabbits, Considering a trio