Commission invoicing and reporting in VTiger CRM

Hi. We are small insurance broker company and currently using VTiger CRM ( setted up on our own) system as our client database. We have few advisers working for us and we need accurate commission payment system. What we are looking for is to develop Invoicing structure avaliable in VTiger (purchase order / sales order / invoicing) to have accurate tool for commission payments. Our process currentlu look like that - an adviser is creating lead which is converted to a contact and account. In contact we are keeping all contact details and personal informations about client and account contain all details about sold products to that client. One client can take few different products - which are paid differently depend on policy type and provider. We are looking for a way that adviser can set some king of commission expectation, but he/she need to be able to set few for same client. We are very open-minded and will concider all reasonable and usefull ways of setting it up. Thanks.