29 U.S.C. § 1398 : US Code - Section 1398: Withdrawal not to occur because of change in business form or suspension of contributions during labor dispute

      Notwithstanding any other provision of this part, an employer
    shall not be considered to have withdrawn from a plan solely
    because - 
        (1) an employer ceases to exist by reason of - 
          (A) a change in corporate structure described in section
        1369(b) of this title, or
          (B) a change to an unincorporated form of business

      if the change causes no interruption in employer contributions or
      obligations to contribute under the plan, or
        (2) an employer suspends contributions under the plan during a
      labor dispute involving its employees.

    For purposes of this part, a successor or parent corporation or
    other entity resulting from any such change shall be considered the
    original employer.