Product Vendors for WooCommerce

I’d love to be able to exclude the sign up fee from the vendor’s commission calculation. I have a marketplace website that sells recurring subscriptions, so I currently edit that very first subscription parent order in the database of the website so I can take that sign up fee out of our vendors’ commissions. I’d love for an easier way to exclude the sign up fee from the calculation of a vendor’s percentage commission.

Thank you!
Julie