An order granting custody to a parent who is receiving, or in the opinion of the court is likely to receive, assistance pursuant to the Family Economic Security Act of 1982 (Chapter 2 (commencing with Section 11200) of Part 3 of Division 9 of the Welfare and Institutions Code) for the maintenance of the child shall include an order pursuant to Chapter 2 (commencing with Section 4000) of Part 2 of Division 9 of this code, directing the noncustodial parent to pay any amount necessary for the support of the child, to the extent of the noncustodial parent’s ability to pay.