Transfer of ownership

Hi,my mama bought property (house) at pune at 1992.he did all documentation sell deed, index, but was unable to apply for 7/12 utara(extract) that time. At present time my mama expired and his family(mama's son and wife i.e my maami) want to sell their property to my father , when we gone to lawyer to transfer all the document he suggested me and my cousin (mama's son) to make 7/12 extract first then buy or sell this property.when my cousin applied for 7/12 in talathi they send notice to old owner , and he took objection on it, i want to know that (1)what all things he(old owner) can do by taking objection? (2)can my cousin's family sell property to my father without 7/12 extract with object by old owner? (3)If No, then what procedure my cousin's family should follow, (4)if Yes,then if my father will apply 7/12 will there be any issue? (5)can my cousin and his family directly sell property to my father or they have to first obtain any hareship ,because currently my mama's(expired) name is on following documents Sale deed ,index2,property tax etc