Hello Roy,

Thank you for your feedback. I am glad that you resolved your issue and I believe that other community members may benefit from this as well.

Thanks again.

I found a solution to this problem, First, I did a "reset" to the ExpansionIndicator by:

xamDataGrid_RemainsOnLine_ReportMode_GroupAccount.FieldLayoutSettings.ExpansionIndicatorDisplayMode = ExpansionIndicatorDisplayMode.Never; xamDataGrid_RemainsOnLine_ReportMode_GroupAccount.FieldLayoutSettings.ExpansionIndicatorDisplayMode = ExpansionIndicatorDisplayMode.CheckOnDisplay;

 Then implements the following code:

foreach (DataRecord rec in xamDataGrid_RemainsOnLine_ReportMode_GroupAccount.Records)
{
     if (rec.ExpansionIndicatorVisibility! = System.Windows.Visibility.Visible) 
     {
          rec.Visibility = System.Windows.Visibility.Collapsed;
     }
}

It might not be the ideal solution, but it does the job.

Thanks Stefan, it works great.
I have another question on that subject, after I make the filtering on the second layout, is there a way to collapes all the records in the first layout which do not have second layer records?
For example: Student A has three grades: 40,50,60 and I perform filtering grade = 80. I do not want to see the record of student A at all (On the first layout).