how to change the purchase order by OCM ?

Hi Experts，

At present, I have implemented the OCM method in SAP to automatically change the components of the production order，but for the system to automatically change the BOM component of the purchase order to use the OCM method, I don’t know. I tried to search for information on the Internet, but did not find the relevant information introduction. Please help, tell the specific operation and background configuration, thank you.

BR

Sun