1. A method for managing relationships, comprising: generating, by a relationship management service executing on a hardware processor, a list of entities that a first registered user has a relationship by: obtaining a credit card statement from the first registered user, extracting a list of merchants listed on the credit card statement, and for each merchant in the list of merchants: sending a first relationship confirmation request to the first registered user to confirm the relationship, and adding the merchant to the list of entities when a relationship confirmation is received from the first registered user in response to the first relationship confirmation request; receiving, by the relationship management service, a notification request comprising contact information for the first registered user, wherein the contact information comprises a physical mailing address; identifying, by the relationship management service, a first associated entity from the list of entities; retrieving, by the relationship management service, a first user update preference associated with the first registered user and the first associated entity from a persistent storage device, wherein the first user update preference specifies whether the first associated entity receives a first update message following a change in the contact information for the first registered user; retrieving, by the relationship management service, a first entity update preference associated with the first associated entity from the persistent storage device, wherein the first entity update preference specifies a first requirement for sending the first associated entity the first update message; making a first determination, by the relationship management service, that the first user update preference permits sending the first update message to the first associated entity; based on the first determination: creating, by the relationship management service, the first update message, wherein the first update message comprises the contact information, and wherein the first update message is formatted according to the first requirement; and sending, by the relationship management service, the first update message to the first associated entity based on the first entity update preference; identifying, by the relationship management service, a second associated entity from the list of entities, wherein the second associated entity is in the list of merchants extracted from the credit card statement; retrieving, by the relationship management service, a second user update preference associated with the first registered user and the second associated entity from the persistent storage device, wherein the second user update preference specifies that the second associated entity receives an update following the change in the contact information for the first registered user; retrieving, by the relationship management service, a second entity update preference associated with the second associated entity from the persistent storage device, wherein the second entity update preference specifies an online form, managed by the second associated entity, for updating contact information for the user; obtaining, by the relationship management service, a username and a password corresponding to the first registered user and required to access the online form; and updating the second associated entity via the online form using the username and the password.