The ability to add a disconnected person to a family tree is a very useful function when you do not yet have proof of a relationship between that person and your main tree. For example - you suspect your ancestor is related to another family of the same surname that lived in the same geographic area. Constructing a detached tree for the purpose of investigating and organizing the facts for the suspected relatives often leads to finding evidence that proves the relationship. At that time the detached branch can be connected to the main tree. Even if no relationship is found, the records and information gathered for the individuals on that detached branch may be of benefit to other researchers, particularly information that has been gathered from sources outside ancestry.com.