An umbrella organization is an association of (often related, industry-specific) institutions, who work together formally to coordinate activities or pool resources. In business, political, or other environments, one group, the umbrella organization, provides resources and often an identity to the smaller organizations. Sometimes in this kind of arrangement, the umbrella organization is to some degree responsible for the groups under its care. Compare to franchises and subsidiaries.
There may be many reasons for establishing/joining an umbrella organization:
Example organizations
References
Umbrella organization Wikipedia(Text) CC BY-SA