Schema files with cyclic references not supported, is it possible to rewrite these?

We are about to integrate Siebel with Salesforce. Salesforce provides an enterprise wsdl file, describing all of their web services and objects. When importing the wsdl file in tools we get one business service containing all of the web services that is provided by Salesforce. I also get the corresponding paired integration objects (request, response). The problem comes with the objects in Salesforce that are defined in the wsdl file within the schema elements. They are defined with cyclic references, why we can't produce these objects as integration objects in tools.

Siebel doesn't support schema files with cyclic references. So these objects are just dropped. Is there a way of rewriting the schema files or is there a tool out there that can be used?