To get the instance of the subform that you are working on you can use this.parent.index. Now when addressing the field the occurance number is on the container subform and not on the field itself. So if you had a Page1 - Subform1 - Row - Object you would use Page1.Subform1.Row[instancenumber].object.rawValue
The only issue is the the [] are illegal in javascript so you can use the syntax:
when i enter a user id in the first row, it populates fine. then i add an instance to my table, and a second row comes up. When i enter a user ID into the second row, it updates the user information in both the first and the second rows, not just the second row....