I attached a sample solution that demonstrates how to persist a hierarchical RadGridView control - in the solution the column, filter and sorting settings are persisted along with the expanded rows of the GridViews in all levels of the hierarchy. In order to implement this functionality you'll need a helper class that keeps a reference of the RadGridView control and attaches to its RowLoaded and RowIsExpandedChanged events to keep track of the expanded rows.
I hope the solution will help, but please let us know if we can further assist you.
All the best,
the Telerik team
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