If—
(a) a child or young person is—
(i) remanded in a youth justice custodial centre; or
(ii) serving, or has been sentenced to, a period of detention in a youth justice custodial centre; and
(b) a warrant to detain the child or young person in a youth justice custodial centre or a warrant to imprison the child or young person in default of payment of a fine or sum of money is delivered to the Secretary—
the Secretary may direct that the period of default be served in the youth justice custodial centre instead of in the manner specified in the warrant.