Add new row in hierarchy Inline grid

Hello my name is Amin, I am new to Blazor and Radzen
I have a question about adding a hierarchy row in RadzenGrid, I could not find the answer in documentation or on the web.
In my case, I have a hierarchy Inline grid to show categories and edit them.
all is well until I wanted to add subcategories in the expanded hierarchy, of course, it is possible to add categories using Grid.InsertRow(...) but I need to add subcategories in each category and because insertRow() isn't working in expanded mode to add subcategories (it is only adding category).
so if anyone could give me a sign it would be very nice...

This is what I also searching for! I want to insert both master and details.