I have a bonded male/female pair.

 We came to care for a third female a while back that has since become a permanent family member.  We would like to explore the option of bonding all three together but I don't know where to start.

 Any advice/resources for adding a third to a pair?

 (All altered)

From what iv heard its best to bond them separately first, so have one original bun in a total neutral place with new bun, then switch over, as they both begin to accept new bun try them all together for shot periodsof time. Although I have heard u need to be careful of the original buns relationship, because obviously you don't want to take a step back with that, sorry I couldn't help more

I would try them separately. You can switch dates between new bun + boy and new bun + girl, or really focus on one pair until they're good, then work on the other pair before trying them all together.

I tried bonding a new bun to a bonded pair and I found it worked best to do what Elrohwen suggested. The new bun (boy) and the boy in the bonded pair never did get along so I quit trying.