Find the properties in mumbai with property owner's name

Though not so easy task.......... but fix some date of ownership record and file RTI with head of townplanning officers, where records of property cards is maintained. ( https://www.e-stampdutyreadyreckoner.com/Property-Card_-Offices-MSD.H T M L), for the property held by your GF on such and such date; Hope, thereby some way may come out.