The adjacent (and not so adjacent) names on a manifest could be relatives. Families with children may bring along an unmarried aunt or uncle. Single immigrants may arrive with a sibling, cousin, or family friend. Search for all names in indexes and finding aids as it may be easier to find one person over another, depending up the handwriting and the indexing. The manifest does not often give the relationship. This is particularly true in pre-20th century manifests and often the case in later ones as well.