Dropping a trailer for local Delivery

The load is from Peachtree City, GA to Mt Vernon, IL. My OTR driver is going to P/U the load Friday and bring it to our office in St. Louis, MO and a local driver is going to do the final delivery Monday so the OTR driver can leave out Sunday night on another load. How do we make sure both drivers get the proper miles? If I change the location on the load then it will change it on the invoice.