If society is not registered by law means as co operative housing service society and the chief of this society and committee are decide in meeting on some agenda but not putting of signed copy of society decision as circular message in whatsapp group of society members against held agenda meeting so it is legal?

No, it is not legally sufficient to communicate decisions taken in a society meeting just by circulating a message in a WhatsApp group of society members, especially if the society is required to be registered under the law. In India, cooperative housing societies are governed by the Cooperative...