Section 101. Liability of relatives to support

1.  Except as otherwise
  provided by  law,  the  spouse  or  parent  of  a  recipient  of  public
  assistance  or  care  or  of  a  person liable to become in need thereof
  shall, if of sufficient ability, be responsible for the support of  such
  person, provided that a parent shall be responsible only for the support
  of  a  child  under  the age of twenty-one years.  Step-parents shall in
  like manner be responsible for the support of  step-children  under  the
  age  of twenty-one years. Nothing herein shall impose any liability upon
  a person to support the adopted child of his or her spouse if such child
  was adopted after the adopting spouse is living separate and apart  from
  the  non-adopting  spouse  pursuant to a legally recognizable separation
  agreement or decree under the domestic relations law.    Such  liability
  shall  not  be  imposed  for  so long as the spouses remain separate and
  apart after the adoption.
    2.  The liability imposed by this section shall be for the benefit  of
  the  public  welfare  district  concerned  or  any  legally incorporated
  non-profit institution which receives  payments  from  any  governmental
  agency  for  the  care of medically indigent persons, and such liability
  may be enforced by appropriate proceedings and actions  in  a  court  of
  competent  jurisdiction.  Such proceedings and actions may be brought by
  such an institution in any court wherein a similar proceeding or  action
  could be brought by a public welfare official.
    3. The expiration of any period of time for the payment of maintenance
  by a court in a matrimonial action shall not be a bar to the enforcement
  of the liability imposed by this section.