What is the concept and meaning of "umbrella organisation"?

Question

Five major Indian American groups have joined hands under an umbrella organisation, that represents a diverse spectrum of Indian American opinion.

Answer 1

Like under one roof it is under one organization dealing in different heads of activity related to each other serving different purpose mostly under a superorganization or managment to achieve a particular goal.
An educational trust running different faculties like medical,engineering, managment,and a hostel facilitating all the students, each independently managed by committees but under the overall supervion of one nodal management.

Answer 2

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. Often in this kind of arrangement, the umbrella organization is to some degree responsible for starting the groups under its care. Compare to franchises and subsidiaries.

There may be many reasons for establishing/joining an umbrella organization;

The ability to carry out activities which could not be accomplished alone, due to
Economies of scale;
A better pool of experts and experience;
Shared apprenticeship and exchange of know-how;
A sense of community and support that makes people and corporations derive utility from multilateral and shared activities;
An increased brand/public awareness.

Answer 3

it means, its an organisation that represents all five organisations under them, so they can accomplish more, since they all have similar goals,