law: Indian Contract Act, 1872 
  45. Devolution of joint rights
  When a person has made a promise to two or more persons jointly,
  
  then unless contrary intention appears from the contract, the right to claim
  
  performance rests, as between him and them, with them during their joint lives,
  
  and, after the death of any one of them, with the representative of such
  
  deceased person jointly with the survivor or survivors, and, after the death of
  
  the last survivor, with the representatives of all jointly.
   Illustration 
  A, in consideration of 5,000 rupees lent to him by B and C,
  
  promises B and C jointly to repay them that sum with interest on a day
  
  specified. B dies. The right to claim performance rests with B's representative
  
  jointly with C during C's life; and, after the death of C, with the
  
  representatives of B and C jointly.