You need to buy the same by paying society the said amount aa per square feet rate. It's discretion of society to accept your request or not

A passage through the flats cannot be converted  into a private property by simply paying the society as it isn't a private property. The two flats are separate and you must have purchased the flats but the passage is still a public property.

Obtain society permission in writing to do so 

resolution has to be passed by society in AGM permitting you to do so

The common passage falls under the definition of 'common area' meant for the use of all residents in an apartment complex. As such you cannot have an exclusive right of use over it, even though you may own two adjoining flats in that complex.

Firstly you will need the society NOC for the enclosure of the common passage 

An EGM has to be convened and a resolution by majority vote has to be passed permitting you for the enclosure on paying the relevant charges as mutually agreed  between you and the society 

The procedure thereafter has to be done through an architect 

The architect has to submit plans for the said enclosure and charges of the BMC has to be paid as converting a common passage into an exclusive area for the joint flat holder would entail consumption of FSI

When building plans are originally sanctioned the common passages are free of FSI, that is not included in the FSI computation 

1. The society has no authority to give any permission to alter the basic structure. What you intend to do is blatantly illegal. 

- If the said passage come under the common area of the society , then you cannot get the permission for the same , and the society cannot sell the said common passage legally. 

- However, you can move an application before the society for the same in order to get approval from GBM.

 Dear Client,

If the passage is a common area of the society, then the society cannot sell the said common passage legally. You can try to get approval from society in writing. 

Thank you

Dear Sir,

Yes, you can purchase and there must be specific narration and description of such passage and if necessary the neighbors signatures may be taken on the sale deed that they are consenting for sale of such common passage which is not being used by any other person except you the purchaser.

The common passage is a common passage and not owned by anyone, it belongs to society.

Just because it runs between your two flats, you cannot claim the ownership of the same until you have purchased the same by a registered document.

If your usage of the said common passage has not been hindered or obstructed by anyone, what is your worry about it.