In addition to comments by others it would also help to better explain the nature of this partnership. It looks more like an informal arrangement where you seem to want to collaborate rather than work as a partnership registered by the authorities. I kind of assume this because you do not really want to fully disclose all financial dealings but restrict it to some information on inventory and sales. You also state you want to sell a mix of your and the collaborator’s items together on one invoice, so should we assume that you use a single bank account? It looks more like a case where your “partner” is more of a supplier that provides you with website inventory on credit until sold. Once sold this “partner” gets paid. Version 21.6.0 Customer portal introduced the first peak of a concept by @Lubos where customers can view (not initiate or edit) their invoices, orders, quotes, credit notes, and delivery notes. Once this concept is further developed it would be useful for cases such as yours that also could be made for Suppliers so your “partner” can see what is going on. I do not think that user restriction settings can be set for specific items and invoices. So the best is to send the “partner” regular reports with the information required.