The term "substitute appearances" refers to a situation where someone stands in for another person, usually temporarily. This can happen when an actor is unavailable or when a musician needs to be replaced during a performance. In such cases, the substitute takes on the role of the original performer and appears as if they were the primary individual. The term "substitute appearances" may also refer to instances where someone makes an appearance in place of another person for various reasons, such as representing them at an event or fulfilling their obligations.