law: 9. Consequences of alteration in the extent of certain Assembly constituencies.-
  If in consequence of the addition of areas to Chandernagore for the purpose of constituting the Chandernagore Assembly constituency, the extent of any existing Assembly constituency is altered, then-
  (a) the electoral roll of the existing Assembly constituency as so altered shall, until it is prepared afresh in accordance with the provisions of the Representation of the People Act, 1950 (43 of 1950), and the rules made thereunder, be deemed to consist of so much of the electoral roll as relates to the areas comprised within that constituency as so altered;
  (b) every sitting member of the Legislative Assembly of West Bengal representing the existing Assembly constituency shall be deemed to have been elected to that Assembly by that constituency as so altered.