Memerbship+MarketPress

I am looking for a way to integrate membership and marketpress. The site is an e-book site. We want to sell the e-book, but also offer a membership to the site as an add-on.

I could add a new product to the checkout for the “membership” as a product, but since it does not tie into the membership system then the content will still be hidden. I realize that I could manually upgrade people that buy the “membership” option as an add-on but curious if there is any integration of these two products.

So, right now I see it as people having to buy the e-book and then come back and make a second transaction to get the updates package so that they are in the system for the e-book and the updates.

David