Sch 1 para 8
(1) This paragraph applies where a child arrangements order to which sub-paragraph (1A) applies or a special guardianship order is made with respect to a child at a time when there is in force an order (“the financial relief order") made under any enactment other than this Act and requiring a person to contribute to the child’s maintenance. (1A) This sub-paragraph applies to a child arrangements order if the arrangements regulated by the order consist of, or include, arrangements which relate to either or both of the following— (a) with whom the child concerned is to live, and (b) when the child is to live with any person. (2) Where this paragraph applies, the court may, on the application of— (a) any person required by the financial relief order to contribute to the child’s maintenance; or (b) any person who is named in a child arrangements order as a person with whom the child is to live or in whose favour ... a special guardianship order with respect to the child is in force, make an order revoking the financial relief order, or varying it by altering the amount of any sum payable under that order or by substituting the applicant for the person to whom any such sum is otherwise payable under that order.