Hello Kiran,
After importing your WSDL, there is a tab called references tab. What you can do is to import the xsds as external definition, then copy the path on the WSDL references tab and then paste it to the Source field in the xsd. If done correctly, once you go to the wsdl references tab, the entries there should point to the xsds imported as external definition.
Hope this helps,
Mark