I wouldn't agree with the use of group check rules with knowledge skills. With a knowledge skill, assuming PCs are sharing what they know, the most important result is the highest one since that's the one most likely to reflect the most information. The group, as a whole, doesn't need to pass the check for that information to be disseminated, just one smarty-pants PC. Putting their heads together, yes, that seems appropriate for help to give the PC with the highest modifier advantage. Running it as a group check would actually make it harder for the PC group to know the information in question.