Well, the AngryGM proposed what I think is a very good way of handling group checks. This one's specifically for D&D 5E, but the basic idea can be adapted.

If only one member of the group needs to succeed for the group to succeed (such as with searching a room), then whoever has the highest proficiency and ability bonus rolls. If any member of the group has advantage, the check is made with advantage, and if any member of the group is benefitting from any bonuses that would apply to the check, the largest single bonus applies.

If only one member of the group needs to fail for the group to fail (as with sneaking past a guard), then whoever has the lowest proficiency and ability bonus rolls. If any member of the group has disadvantage, the check is made with disadvantage, and if any member of the group is suffering from any penalties that would apply to the check, the largest single penalty applies.