Hi Truman,
Thanks for using Syncfusion products.
Your requirement of using LINQ as datasource in GridGroupingControl can be achieved by PassThroughGrouping feature.When a grid is not bound to pass-through grouping by default, it will retrieve all the records in the bound data source to the client, even if only a few of them are displayed in the current view. This could become serious overhead when dealing with large data sources. To overcome this, instead of binding the grid to the data source directly, bind it to the LINQ query results. When you do so, data from your data source is retrieved on demand when a user requests it. Please refer to the below code snippet.
[ASPX]
runat="server" GridGroupingControlID="GridGroupingControl1"
SelectTable="Orders" SourceContext="DataClassesDataContext" >
Your requirement of showing add new record after details can be achieved by setting the property ShowAddNewRecordAfterDetails to true. Please refer to the code snippet below.
[ASPX]
Please refer to the below link to download the sample application.
http://www.syncfusion.com/downloads/Support/DirectTrac/86943/Passthroughgrouping171522482.zipPlease let me know if you have any concern.
Regards,
Ranjithkumar.