A "Welfare Association" is registered under the Societies Registration Act of the State. This Act is intended for voluntary organistions, where members voluntorily come together for a common purpose. An Association of the residents of a building or building complex is not a volundary organisation. Membership of the Association is compulsory and the subscripttions are also compulsory. In Tamilnadu there is Tamilnadu Ownership Flats Act, 1994 framed for the purpose of apartment owners. But it is mostly ignored by flat owners. Now I shall try to answer the questions raised here
1. whether the decision of resident welfare association should have approval of majority of apartment owners or Majority of the governing committee members.
As per the byelaws, articles of association or by whatever other name by which it is known, the decision making powers will be distributed between the Managing Committe and the General Body of members. Who has the power will depend on the matter that is being decided upon.
2.whether every member of governing body (including president, secretary, treasurer and other members) need to be elected by majority of apartment owners or nominated/ proposed by a few owners.
Generally the office bearers will have to be elected. There can be specific provisions for co-option also.
3. whether legally valid RWA / apartment owners association can be formed after 15-20 years of existence of apartment complex.in tamilnadu.
An association can be formed and registered at any time provided previously there was no registered association. But as I stated in the beginning a "Wefare Association" is a volunary organisation and there is no law to compusorily make a flat-owner or a resident, a member of such association and be governed by its byelaws. But if you register under the Tamilnadu Ownership Flats Act, 1994, yes, you can compel every flat-owner to become its member. Each member will also get the rights of owner of an immovable property.