Wiktionary
supraorganization
n. An organization whose members are themselves organizations
Wikipedia
Supraorganization
A supraorganization is an organization whose members or stakeholders are organizations rather than individuals and which performs an over-arching function.
Some organizations may have membership of both organizations and individuals. These are usually described as " federations". " Coalitions", " networks", " confederations", and " unions" are also terms that are sometimes used, although these are just as frequently used to refer to organizations composed of individuals.
The term is also used in microbiology.