What I really want to do is ability to display a different context menu when right clicked on the groups, and ability to rename or delete groups. 

Hello ChiliBiscuut,

It has been a while since you have made your  post, in case you still need of support I will be glad to assist you on this matter. I suppose the other community members can benefit from this answer as well.  So I researched your issue and I believe that the GroupByRecordPresneter control doesn’t contain recordSelector element. In order to achieve your requirements I believe that you can retemplate the default style for the control and add RecordSelcetor before the content. You can find the default templates for the control in your coputer in the file C:\Program Files (x86)\Infragistics\NetAdvantage 2011.1\WPF\DefaultStyles\DataPresenter\DataPresenterGeneric_Express.xaml. Also you can modify the control that shows the content and turn it form ContentPresenter to a TextBox, so it can be edited. Please have a look at the attached sample, where I show you the described approach to add a RecordSelector and I also add a ContextMenu that when you right click on the group by record. In the ContextMenu you can chose ”Delete” in order to remove the record.

If you still need any further assistance on this matter, please do not hesitate to ask.