The present disclosure relates to a method, performed in an accessory device, for monitoring the current operating state and the future operating state of a base plate of an ostomy appliance. The accessory device comprises an interface configured to communicate with one or more devices of an ostomy system. The interface comprises a display. The ostomy system comprises a monitor device, and/or the ostomy appliance configured to be placed on a skin surface of a user. The ostomy appliance comprises a base plate. The method comprises obtaining monitor data from the monitor device; determining a current operating state of the ostomy appliance based on the monitor data; determining a future operating state of the ostomy appliance based on the monitor data and/or the current operating state; and displaying, on the display, a first user interface screen comprising a first primary user interface object representing the current operating state and/or a first secondary user interface object representing the future operating state.