Associate Member is a concept for the society or association alone.
It will not mean that you become the joint owner of the property.
The property is owned jointly by your parents who have purchased the property by a registered sale deed.
The registered sale deed is the title document.
Since your name is not in the title document, you cannot claim tittle to the property and the associate membership in the society cannot entitle you to own the share of your property.
The share of your father in the property, who is reported to have died intestate, shall devolve equally on all his legal heirs, i.e., your mother, you and your siblings.
If you want to own the property entirely by yourself, then your mother has to first execute a registered gift deed in respect of her share in the property and after that your mother with all your siblings should execute a registered release deed relinquishing their rights in your father's share of property in your favor.
Mere NOC from your mothe and siblings will not be sufficient to make you the absolute owner of the entire property.
You have to follow the above suggested steps to acquire the property on your name to become an absolute owner of the entire property.