1. A computer-based method of registering a person in a person registry as a shared entity or a non-shared entity, comprising: if a unique person identifier is not received, searching an address book for a match to the person using a search criteria input by a user; and if no match to the person is found, receiving person data input by a user and determining whether the person data satisfies a minimum data requirement, wherein the person data is representative of the person, if it is determined that the minimum data requirement is satisfied, determining whether there is a shared entity that represents the person, and if it is determined that no shared entity represents the person, based on an outcome of a non-shared entity-shared entity reconciliation, either defining a shared entity to represent the person in the address book, transforming a non-shared entity into a shared entity, or transferring data from a non-shared entity to a shared entity.