Creating a child record from a button on the parent form and automatically return back to the parent form after the child has been saved.

The problem is the the URLTWO

var text URLTWO = URLRoot() & "db/" & [_DBID_DAMAGE] & "?a=dr&rid=" & [Related Damage];

Stop and think about where is the user is when they push this button. They are sitting on a damage parts record. The record that you want to display is in the table above that which is called damage. The record ID that you want to display in the damage table is in fact the parent of the damage parts record. And that record ID is likely called [related damage].