Click New Group on the Results tab. A new group called New Group X is added above the currently selected clash (or at the top of the list if nothing is selected).
Type in a new name for the group, and press Enter.
Note: Clash groups are identified with the icon.
Select clashes you want to add to this group, and drag them into the group.
Note: When clashes are grouped they are treated as a single clash in the count at the top of the Clash Detective window. Each clash group is counted as a single clash unless no clashes have been added to it, in which case it will not be included in the count.
When you click the created clash group, the two panes in the Items panel show all the clashing items contained within that clash group, and all corresponding clashes are shown in the Scene View.