XSD and references to additional namespace

Hello,

I have a list of XML files with statistics and glue these files for
output using XInclude. Also all files are based on some XSD Schema.

Unfortunately I have found only one solution to get my XSD Schema
validation running with these elements referencing the external XInclude
namespace:
I downloaded the XInclude schema into a local copy xinclude.xsd and
import the namespace via
<xsd:import namespace="http://www.w3.org/2001/XInclude"
    schemaLocation="xinclude.xsd" />
and declare references like
<xsd:element ref="xi:include" minOccurs="0" maxOccurs="unbounded" />

Managing local copies of the standards I want to reference sounds quite
scary to me, is there any other option or better solution?

Thanks in advance.

-- Dennis Sterzenbach