Reading between the lines here, I'm assuming you have or are creating a multi-vendor marketplace (e.g. Etsy, Devot:ee).
Every site I've seen do this using ExpressionEngine takes the money first, and pays out its vendors at the end of the month (as Devot:ee) do. While PayPal Adaptive Payments sounds like a nice idea, it makes it much harder to effect refunds etc, especially when customers come to you with a complaint about the vendor which you must resolve.
Without more information it's difficult to make a recommendation. Any decent PHP developer should be able to add Adaptive Payments support for you (and you would probably hard code into the extension some logic for looking up the Paypal seller email address in your database, then calculating the correct payment split etc, so it's not really something that would ever come built in to an e-commerce plugin).
However, you may find it's easier to simply pay out your vendors monthly, at least until your site grows to a point where it warrants a completely custom build (in a PHP or other framework, rather than a CMS).