Hello,
Thank you for your message. While Adaptive Payments has been discontinued, there is a new product that offers some of the same features. You can find out more about PayPal for Marketplaces here.
https://developer.paypal.com/docs/marketplaces/pp4mp/
One of its main features is Partner Fee which sounds like what you are looking for:
https://developer.paypal.com/docs/marketplaces/orders/integration-guide/
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