Hi Piet,
Have you looked at the commercial offerings by Attunity? Here are a couple of links you can check out:
http://www.attunity.com/adapters_for_biztalk_server
http://www.attunity.com/tuxedo_adapter
I’m not sure if that’s what you are looking for to re-architect your data exchange processes, but it’s worth taking a look.
Daniel.