Add new Credit Check Rules

I need to add two additional Credit Check Rules in SAP, one is for "regular" Payer accounts, the other is for Parent Payer accounts. These both should regulate the credit check process on orders such that the system will place an order on credit hold if one or both of the following are true: a customer is over their credit limit and/or an invoice on a customer's account ages 15 or more days past due.

Can someone tell me the transaction code and specific procedures to fulfill it. Very much appreciated!