Can mother transfer mortgaged property to grandson through will

My father, owner of self acquired property transferred his home in my mothers name who is housewife. my elder brother has taken a loan of 20 lacs with my mother as co-applicant for house construction. Me n my elder brother both are paying the EMI equally. So, even if the loan is in my mothers name (in whose name the property is registered) and my elder brother, the EMIs are paid by me n my elder brother. Now, my mother intends to transfer the house to her grandson (son of my elder brother) by way of WILL, leaving me out of that. is it possible, can she make a will evn if property is under loan