On a button click, is it possible to add new rows under each parent row?

Indhu

Once the rows are created under the Parent row, Is it possible to add row data using the intake form?

brianschmidt

Are you able to provide more context and perhaps sharing a screenshot of the sheet you are working with (with sensitive data redacted)? Assuming you are using the form feature, each new form submission will appear as a new line as opposed to adding to already created lines.

If you are asking if new lines (aka new form submissions) will automatically be indented under a parent row, I do not believe they will and there are no automation settings that allow you to automatically adjust row hierarchy.