Transferring a credit balance

How would I go about transferring a credit balance from one Vendor to another in Sage?

We work with a Vendor that has a Concrete business and a lumber business and our records have each of these subdivisions as a vendor in Sage. Currently we have a credit balance with the concrete company but we have an outstanding balance with the lumber company. Is there a way to transfer this credit balance in Sage from one Vendor to the other?

Thank you

Rhiannon