I think if they do split, the grouping that makes most sense is
Rumple, Snow, Charming
Regina, Hook, Emma
Regina and Rumple would be at each other’s throats, as would Rumple and Hook- plus as has been said, it would be best for each team to have someone with magic. Hook likes Emma and Regina tolerates her better than she does any of the others. The Charmings are the ones Rumple is least likely to want to kill. Emma would be included in that, but I think she needs to be there to keep Regina and Hook in check.
[adrotate group="5"]