1) Your share will be 50% share in the property and for remaining 50% share of mothers all legal heirs share will be in the property including you.
2) Distribution if mother's share among in all legal heirs i.e. all will be get 25% share in the that 50% means 12.5% each of total property.
3) So your share will be 50% + 12.5% = 62.5%
4) After inserting all sisters name on the property have to make relinquish deed and remove their name from property.