using "owner" in task assignments - not resetting to new owner

I am trying to create a return path on PR's so that an engineer can reject the verification step as being out of their scope. When it goes back a new owner ID is assigned to the ticket and the task is completed. In my workflow diagram, I set the assignment to the Owner. When it reaches that workflow state, the assignment is changed to the owner ID. Thus, when that person rejects it back and a new owner ID is set on the item, the assignment is still assigned to the old owner ID. I need the "assignment" to stay on owner and not change itself to the user ID. It seems like the thing to do is to write a server method to reset the assignment back to "owner". I just wish it wasn't changing my assignment from something generic to a literal user ID. Am I missing something here? Is there another way of doing this? Could someone help get me started on writing this method if that's what I have to do?