Inflows and outflows in a marketplace

I have a marketplace business with to models:
(1) I buy a product from a vendor and resell it to customers.
(2) "Amazon" model: I sell products from 3rd party vendors, from which I take a marketplace fee. The final customer pays an inflow amount, I substract my fees and the transfer the remaining to the vendor. I then generate an invoice for the said fees to the vendor. If requested, I also generate "payment notes" for the customer, although the actual invoice can only be generated by the vendor.

How can I use Akounting for the second model, given that those inflows and outflows are not actually incomes and expenses, rather only the fees are my incomes. Should I assign them different categories?