The phrase "were a member" can be replaced by several synonyms which convey the same meaning. Some of the synonyms include "belonged to", "were part of", "were included in", "were affiliated with", and "were enrolled in". Each of these synonyms may be more suitable to use in a particular context. For example, "belonged to" could be used when talking about a social club, while "enrolled in" could be used in reference to a class or course. Choosing the right synonym to replace "were a member" can help to add variety and richness to sentence structure and style.