Transferred property can he sell property without owner's knowledge

my Father had own the property in 1987 which was illegal later due to personal reason we leave that Property and shift to other place and Handed Over the property to my Aunty. (she was alone personal for her future life) and there was no paperwork we had or we didn't transfer the ownership to her now she want to sell that property to some one Else without consulting to us To Prove that it was own by us we having below Documents : 1. Agreement paper with Old Owner ( it was on Simple Paper with Stamp) 2. residential Committee Bills Pay by us 3. Old Rationing Card