6. In relation to an applicant under section 20 of the Act of 1978 for the variation or revocation of an order under section 11(3) of that Act pursuant to an application made before the relevant date, subsection (12)(b) of the said section 20 shall have effect as if the words “a parent of that child but” were omitted and for the words “that parent” there were substituted the words “that person”.