Hi Mohammad,
Thank you for writing.
The visual inheritance is not supported by our controls and you cannot build the controls in such way. In this case, you should either set up the grid in the user control or add it directly to the form.
This is valid for the standard controls as well. You can test this with the standard grid.
Please do not hesitate to contact us with any other questions or concerns.
Regards,
Dimitar
Telerik by Progress