We run a study-travel agency and write invoices to partner institutions for referral services. The commission for each referral is dependent upon the price that our referred customers pay to our partner institutions  in tuition and fees for their study program. The percentage we receive in commission also varies from contract to contract. Therefore, the cost of the commission we invoice each partner for essentially the same service (product) is never the same.

Is there away to manually input the product name and cost  into the invoice case-by-case without having to create a new product every time we invoice our partners?