Hello Kai,

Thank you for posting in our forums!

In the WebHierarchicalDataGrid you can access the root ContainerGrid object by referencing the WebHierarchicalDataGrid control’s GridView property . Further, you can access a row’s child ContainerGrid objects by using the ContainerGridRecord object’s RowIslands property.Please note if you are using Load on Demand, make sure that the ContainerGrid exists; i.e, the parent row is expanded before trying to access the row island. There are several ways to select a row after enabling row selection: you can select a row by clicking on a cell in that row or you can also select rows in code by adding them to the selected rows collection.

When you want to get the selected rows from the child grid, then you need to iterate through the grid’s row collection and access the current selected child bands through the RowIsland Selection Behaviors, I just modify the code statement you provided:

ddgProduced.GridView.Rows[1].RowIslands[0]..Behaviors.Selection.SelectedRows.Add(ddgProduced.GridView.Rows[1].RowIslands[0]. Rows [1]);

Please refer also to the following documentation article about the Selection behavior of the WebHierarchicaDataGrid

http://help.infragistics.com/doc/ASPNET/2015.2/CLR4.0/?page=WebHierachicalDataGrid_Selection.html