Da and paaa signing by co owners of flat in coop hsg soc in mumbai

What is the problem in giving her share of one third amount that your mother would be getting in this connection.

If you want to proceed smoothly then better avoid such petty disputes which may hinder the entire process. 

You shall proceed the issue amicably.

As a mother, she may forgo 1/3 rent, shifting charges, brokerage etc, and look for accommodation, utilising 2/3 of funds, as I would  not claim, as I feel she is entitled the whole.  She will be forced to live at far far place from Andheri where she has had lived her life as the 2/3 transit rent amount will not be sufficient to live in a nearby locality in Andheri. 

I feel she, a senior citizen, is being treated unjustly by my sister. Is there no legal remedy? Can my sister use threat of non co operation in signing  DA and PAAA? Cannot DA and PAAA be registered without her sign when her name, share is retained? That was  my query. 

What stops you to take care of your aged mother with you and let her enjoy entire share leaving your sister's share with builder / developer, if she do not agree, for amicable settlement ??? 

You are venting out the grievances against your sister alone and at the same time you are not whispering about the monetary  support that you may extend to your mother besides giving away your share in the rental amount.

If you are so much concerned then nothing prevents you to take care of your mother at her evening period of her life