Apple trade in

I recently bought the iPhone XR, and I have decided that I would like to buy the iPhone 11 instead. I used the trade in (of my iPhone 7 Plus) service when buying the XR. I have received the XR, I have not sent back the trade In iPhone yet. As I would like to buy the 11 and refund this XR; my question is can I cancel the trade in of my old phone 7 plus for this XR and transfer the trade in to that of the iPhone 11