You can add new sponsors through Daily Agenda → Add New Daily Agenda in the WordPress Administration Panel.
Unlike other post types, sponsors do not contain most of the same options as standard posts. They support only a few specific fields.
Schedule Options are found below the title on the Edit Sponsor page. If the Schedule Options are not visible, make sure they are checked inside the Screen Options area at the top.
Press the Add New button in order to add a new session for this day.