@Author
Sister has no right on your property but she would lay claim on her father's property.
However you should understand that if your father invested from his self-acquired property then no one can claim unless there is no "partition". Also when there would be a partition, your father's property shall be divided into equal parts for all share holders like your mother, you, your sister and father. So, the calculation would be as below:
Suppose the value of the property is Rs.100, and S no. of share holders, then:
Your share = Rs.50 (your seperate share) + Rs. (50 / S) (share from father's property)
Your father's share = Rs. (50 / S) (after partition)
Your Sister's share = Rs. (50 / S) (after partition)
Your Mother's share = Rs. (50 / S) (after partition) .............. and so on!
All the best!
//peace
/Saurabh..V