What Xi TV Box To Use with TV Service Downgrade

I currently have a 2 TV set up.  One newer TV uses an Xi6-T Wireless box with an HDMI cord.  An older console TV with only cable in uses an XG2v2-P box.  Current set up works fine.  I recently downgraded my TV service from Ultimate to TV Plus.  As part of the order I was sent a XiD-P box.   That was unexpected as I thought the service could be downgraded with the existing boxes.  Does the new box need to be installed for the service to be downgraded?  If yes, my understanding is that it is a secondary box and would replace the existing one on my old console TV.  If no, Do I just return the XiD-P box?  Any help or feedback appreciated to eliminate an extra box charge or a service call.