Your fathers property is not comes under the head Ancestral property. Property inherited upto 4 generations of male lineage (i.e., father, grand father, etc.) is called as ancestral property. The Supreme Court of India has said that women do not have the right to inherit ancestral property if their fathers died before September 9th, 2005. The view of the Supreme Court is that amended provisions of the Hindu Succession (Amendment) Act, 2005, do not have retrospective effect. The father would have to be alive on September 09, 2005, if the daughter were to become a co-sharer with her male siblings.
After the death of your father his property equally distributed among his legal heirs. In the present stage mother was died and one unmarried brother was died so the property distributed among 4 Son and 3 Sisters equally.
You could not ignore their valid claim over the property. If they file a partition suit you will constrained to give their share