Here is the scenario I would like to implement:

User has a default dashboard, with Customise functionality which would:

• Allow the user to move and resize items (same as now)
• Add / remove item, adding using a drag and drop function from a set of tile types, for example exposed in a TelerikList component. Removing an item with a "delete" button or similar.
• Customise tiles, for example a time period on a chart.
• Save the state of the dashboard.

For loading and saving the dashboard with each tile having a specific content the easiest way I can see would be to bind the TelerikTileLayout to a data source:

<TelerikTileLayout Data="@TileData">

<TileConfiguration></TileConfiguration>

</TelerikTileLayout>

The data would be updated as and when the user configures their dashboard. 

For dragging and dropping new tiles a set of events would be necessary, both on the source tile list, e.g. OnDragBegin and on the tile layout OnDrop.