Scenario: I have a TableA, TableB, and TableC. TableB has foreign key references to TableA and TableC. The collection I'm assigning to my esDataSource is a collection of TableB items, but the pertinent information is actually contained in TableA and TableB. I can display this information no problem in my GridView by using Eval("UpToTableAByTableAID.fieldName"). My problem is that I need to be able to sort by these field names as if they were actual columns in TableB. I've tried the extended properties as in this example: http://www.entityspaces.net/portal/Forums/tabid/105/forumid/60/tpage/1/view/topic/postid/895/Default.aspx. Everything displays just fine, but apparently sorting isn't supported using this method. Are there any other ways to do this, or is this a completely inconceivable, you-must-be-dreaming kind of an idea? Thanks