Transfer of flat by wife of deceased without following legal process

Flat owner died intestate ... and without making any nomination in society records ... NRI wife thereafter without approaching society enters into agreement for sale with Purchaser on behalf of her NRI minor daughter .... n also executes Power of Attorney in favour of the Purchaser .... Both Agreement for Sale and Power of Attorney are registered documents .... thereafter all 3 approach High Court Mumbai ... wife get Guardianship Certificate and Authority to execute final sale deed of Flat on behalf of minor daughter .... Purchaser thereafter executes final sale deed ... n registers it ... signs as both Vendor and Purchaser on strength of previous registered Power of Attorney ... Purchaser has now approached society on the basis of having purchased the Flat from wife and daughter of deceased Flat owner ... What options does the Society have ?