1) was it self acquired property of your father ?
2) how was transfer made ?
3) was it by gift deed duly stamped and regd?
4) on what basis you say father was not of sound mind ?
5) merely because father was suffering from cancer does not mean he was not of sound mind
6) you can file suit to sert aside gift deed if it was vitiated by fraud or coercion or your father was not of sound mind
7) you would have equal share in the properties as Ill legitimate child