thank you for your effort! Unfortunately I discovered that the way you create orders and handle commissions is not applicable to marketplaces in Europe. I don’t know for other countries but this is how it should work in most cases.
Best practice is Amazon Marketplace:
Amazon is the Marketplace and sellers/shops are able to sell their products, in order to do that, they have to pay a fee (%) for each sold item plus additional 30-40 Euro per month. You called that “admin fee”.
As a marketplace owner I don’t want to be mentioned on the invoices to the customer, because I don’t sell the products to them and for legal issues.
So first Invoice would be: Vendor to Customer (no commission is shown to customer, obviously). If the order consists of multiple Vendors, there should be individual invoices for each vendor.
Most important
Second Invoice: Marketplace to vendors for charging the admin fee. It must be possible to set taxes for commissions/admin fees. So for example if the admin fee is 10%, I have to pay taxes (let’s say 20%) of that 10%. Currently this is not possible with WC-Marketplace.
If you put this in consideration, we will be able to use WC-MP and also willing to support.