1. your parents are the co-owners of the property
2. both have equal 50% undivided share in the property
3. after demise of your father, his 50% share will devolve on his legal heirs
4. as per law, his legal heirs are his mother, widow and children
5. thus your father's 50% share will go to his mother, your mother, yourself and your 2 siblings equally
6. consequent to the above your mother's share will increase from 50% to 60% and the balance 40% will go to your GM, yourself and your 2 siblings having 10% share each
7. for transfer in society records, most society will ask you to submit a legal heirship certificate or a letter of administration
8. however if there are chickens sitting in the managing committee of the society then they take some stupid affidavit or indemnity and ask the applicant to issue some public notice and then transfer the flat to the name of the desired person after considering the NOCs of other legal heirs, which is a completely misconceived procedure
9. the procedure at point no.7 is expensive but confers a proper title whereas the procedure adopted by some stupid societies as per point no.8 is cheap and confers no proper title. The person would face issues in future if he has to sell the flat
10. the petition for heirship certificate or LA has to be made in the Bombay High Court