I attached the screenshot for better understand. I want to add a row search on the second or child row. But I'm getting search only on the first row. Look into my screenshot.
The rule that determines which rows will be displayed when a row filter is applied is implemented in onRowFilter event handler. You'll need to extend it to include text of the additional rows as well.
Please note that there is no built-in onRowFilter implementation. The reason is that everyone wants a slightly different behavior.