Under Section 22 of Hindu Succession Act, such right has been conferred upon preemptor even before actual transfer if any of the heirs of Class I proposes to transfer his undivided share - Even if transfer has taken place, right of preemptor under this section is not lost -
2) your father can file pre emption suit
3) section 22 confers a right on Class 1 heir only to seek the transfer of property in his or her name when the other coheir proposes to sell the property. This Section is also applicable to the interest already transferred, but the intention of enacting the Section is to see that the property will remain in the hands of coheirs only and to prevent the strangers from acquiring any interest of the coheir. Further it is clear that the provisions of this Section are confined only to Class1 heirs specified in the Schedule. It is only a personal right given to one or other of the coheirs. That right is neither transferable nor inheritable.