Church records often contain more than just details of births (or baptisms), marriages, and deaths (or funerals). They may contain lists of individuals who were members of the church–even for a short time. They may contain lists of individuals who took communion or made a donation. Any of those lists could be clues–perhaps clues to other family members who lived in area a short time or attended the church for a short time.
There can be a great amount of variation in church records. The key is not to just rely on records of “vital events.”