My husband has been on child support for 9months before we were married we were split up and he never sighned the birth certficate so the court has

This is your husband's case.  You cannot do anything in relation to it as you are not a party to the case.   He can file a supplemental petition for modification of child support - he has no duty to support step children so that will not be credited to him, however, if he has additional children of his own, those could be considered.  He must file that supplemental petition in his child support case for the court to review any of his financial changes - there are certain allowances that can be made under the law.     Thank you for your inquiry.