SSRS custom groups

I've created an rdlc in Visual Studio 2013 and am getting close to having it like I want it, but I need to create a custom group and am not seeing a way to do it successfully.

I've grouped by GL Company (several other groups, but GL is the outer, main group).  Now I want a group where the GL Companies are reporting in 2 divisions, say east and west.  So GL Companies 1,2,3,4 are the east and GL Companies 5,6,7,8 are west.

I created the Parent Group and don't know how to get totals for east and totals for west....  In the Group Properties I can use the filter to get one or the other, but adding both removes the detail from the report.

Please help.

Thank you,
GroupProperties.pdf