Hi Awais,
Thanks for contacting Syncfusion Support.
QUERY: Programmatically add new row with child in TreeGrid
From your query we understand that you need to add both parent and child record programatically to TreeGrid. This can be achieved by using "dataSource" property of TreeGrid.
Please check the below sample,
In the above sample, we have added new record to Treegrid along with it's children in button click. When you click the button placed above the TreeGrid, new record will be added.
If you have further queries, please get back to us.
Regards,
Farveen sulthana T