If:
(a) the ART has reviewed:
(i) a decision (a child support decision ) on application referred to in section 89 of the Child Support (Registration and Collection) Act 1988 ; or
(ii) a decision on application referred to in section 131D of the ART Act in relation to a child support decision; and
(b) that review involved (wholly or partly) a review of a determination to which a care percentage decision relates;
then, despite section 54 of the ART Act, the ART must not, on ART review of the care percentage decision, vary or substitute the decision in a way that would have the effect of varying or substituting the determination referred to in paragraph (b).