I am not absolutely sure if I understand your requirements but if you want to apply a filter to RadGrid that is not generated by its built-in filtering, you could try the folowing:
- Trigger a filter command by using the FireCommandEvent method.
- Then, you can apply the custom filter expression to the control and rebind it, as done in the Example 2 code-snippet in this help article.
I hope this helps.
the Telerik team