Hi Dinesh,
Greetings from Syncfusion.
By default, Grid supports a Custom Command column to add buttons to the Grid columns. We have already discussed about adding custom command in the Grid column in the following Help Document.
We could see you would like to add a record to its child record to respective parent data. In the command button’s click event, we can add the record to the childGrid.dataSource.
We couldn’t see any attachment in your update.
Regards,
Seeni Sakthi Kumar S