To Add a New Relationship between cases that are already entered into Collaborate, click the link within the Associated Case Actions section of the left-hand sidebar.
Clicking Add a New Relationship will direct you to the Associated Relationships creation page.
If the person is already associated with an existing case, you can select the associated person from the Existing Associated Case dropdown (1). If the person you are trying to associate the case with is not found in the Existing Associated Case dropdown, type the person's name into the Search All Cases search box (2) and select the name when it appears in the search results. Once you have selected the person, be sure to indicate the relationship between the two cases (3). To save the relationship click Save (A). To save the relationship and add another new relationship between two existing cases, click Save and Add Another (B).