Can my mother transfer unregistered property purchased on GPA to my sister without my consent
First of all the unregistered GPA is not a valid document, hence she cannot transfer the property to anyone's name becasue she herself if not an absolute owner of the property.
The GPA holder is not a porperty owner and they do not have marketable title to the property.
Is it a valid transaction if property is transferred to my. Sister (married)
She cannot transfer the property and if she does,m then it is not valid.
Can my a mother disown his son from this unregistered property purchased in GPA (if not transfer to daughter)
The mother or the property owner has discretion to transfer or dispose the property on his/her name to anyone of their choice or desire.
Th third person cannot claim any share in it as a right.
However in this cse your mother is not a legally recognised owner of the property.
What legal rights I have to make my stay continue in this property along with my wife and 6 month old baby girl.
You dont have any rights in a property which do not legally belong to you.
Under which section my mother can file a suite to vacate the premises.
If she is the legally valid owner she can very well file an eviction suit against you for staying in the property