Hi Paolo,
Unfortunately, we do not have a working example of the discussed scenario, but in general, you can call the custom logic my colleague suggested in any custom event handler (e.g. a button click), as long as the parent Grid and its details Grids are initialized (the latter happens when a master row is expanded for the first time).
I hope this helps, but if you need further assistance, please send us an isolated runnable project, demonstrating the issue, so we can provide further assistance.
Regards,
Dimiter Topalov
Telerik
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