1. your father had 50% share in the Mira Road Property
2. on his demise, his share would go to his legal heirs as per intestate succession, as no Will was left by your father
3. the legal heirs of a Hindu male are his widow, mother and children
4. i assume your paternal grandmother died prior to your father
5. therefore the only legal heirs entitled to claim the 50% share of your father would be your mother, you and your sister
6. thus you had 1/3rd share in the 50% share of your father
7. as the property sold was located within the jurisdiction of Bombay high court, his legal heirs were required to obtain letters of administration from court and have transfer deeds executed and registered in their names so that they would get a clear title to their respective 1/3rd share
8. as the above procedure was not followed, the buyer has not got a clear title, in absence of letter of administration and consequent transfer deeds
9. anyway, now that the property is sold, it is to be seen whether you were made a confirming party to the sale agreement between your mother and sister on one hand and the buyer on other hand?
10. or is there any written confirmation by you wherein you had consented for your 1/3rd share in the property to be sold?
11. if there is no written confirmation recording your consent, then you can always deny that you had ever given any such consent and thus contend that your share was sold by your mother and sister without your knowledge
12. however the only problem would be period of limitation. If your share was sold without your consent, then you were required to take legal steps from the date of registration of the sale agreement with the buyer
13. if that period is crossed, then your mother and sister can always say that your claim is barred by limitation
14. another plea which you can take is that you had given consent only for selling your share but not for appropriating the same by your mother and sister for purchase of a new house by excluding you
15. as they are denying your right in the new house, you can file a declaratory suit in court to claim your share therein to the extent of your share of sale proceeds realised on sale of Mira road flat. In this way the bar of limitation will be taken care of
PS: Kindly excuse for my previous reply as I inadvertently did not notice that you had written 'late father' in your query and hence i asked that question