Actually, it's easier to create tasks and missions for specialized, thematic groups. A set of four random characters or a set of four characters without a distinct dynamic is far harder to deal with than those of 3, 2, 4 and 3. Four characters is generally considered the most-appropriate amount for a group. The specific setup for Krane's group is that he has the nonbender initiates. The Ostrich group is follow their leader, Sir Ostrichworth the Third, Savior of lower Tu Zen. That leads the airbending masters, Shila, Nicias and Kalani.
My thought is to team Yan, a new initiate and former Air Nomad/Monk, with Rabten, a respected member of the Rising that lent his knowledge and resources to the Rising in hopes to liberate confiscated knowledge held by the Phoenix Kingdom in Ba Sing Se. Reasoning being, who better to deal with a near-master airbender than a former master. Yan still is technically a recruit, and for all his promise, he still has to be assessed. Rabten, being an expert and likely being able to take him one-on-one, given Rabten is still a master despite his age while Yan never mastered the final tiers, as well as delved into the spirituality of airbending opposed to its technique, makes him the best potential candidate. Additionally, this makes their dynamic the wise old men, and if SlowPlow was to return, he would make a good combination with these two. I find it easier to work with these two than any other combination.
Which would leave Shila, Kalani and Nicias. I have no idea in the world why those three would be on a team; two of them are recruiters. However, everyone on the team should be perfectly suitable of plotting with themselves, so the dynamic could be interesting. I'm not closing this RP, so having two recruiters on one team will allow stability for if I have to take one away and do later restructure. This is my avenue of safe expansion, which is best for the health of the roleplay. I would prefer several smaller groups anyway, and we might pick up more RP'ers as the IC ball gets rolling. That said, I believe the best structure currently would be:
Ostrich Group
Krane, Tanvi, Lien
Rabten, Yan
Shila, Nicias, Kalani
I don't believe I'm forgetting anyone, as Aiden and Tao are suspended, and many roleplayers dropped out after not getting the exact character they wanted. I'm looking at this through the standpoint of roleplay structure, social engineering and of course just how interesting the character dynamics will be. In a way, Kalani, Nicias and Shila are all SO different from each other that they FOIL each other in several ways. Nicias, a sandbending thief. Kalani, a waterbender from the Northern Colonies. Shila, an ex-Dai Li. Right there, you have the law enforcement-criminal dynamic and the water tribe vs Phoenix Kingdom resentment. I guess Nicias has no reason to clash with Kalani, but the team itself is interesting. Especially since Uquo would leave Shila as its lead.