Validate the WSDL in a third party tool like Eclipse or XMLSpy or any other XML Editor. See if it passes the validation. If you can, post the WSDL here.
There are ways to make changes to the WSDL (make it a valid WSDL) and import it in to webMethods and it will work as long as your SOAP request is meeting your partner specification, in this scenario your partner does not have to change anything. You will not be able to completely use the documents or the connectors generated by WM from the WSDL but you could do the SOAP over HTTP\HTTPS by composing the SOAP data.
Changing the WSDL from your end and going the SOAP over HTTP is a slippery slope and there is no meaning of using a web service, if it is not conforming to the specifications in the WSDL.
Cheers,
Akshith
#soa#webMethods#API-Management