try to schema validate xml files that i can't change

[dennis luehring]

my environment:

C++, Xerces C++ 3.1.1 using xercesc::DOMLSParser for Xml validation with 
cached grammar - works fine like it should BUT...

my scenario:

i've got an "old" applikation database containing many different xml 
files (without schemas) and i want to use the data validated in my 
applikation, but sometimes the namespace is miss-used (empty, 
non-existent) so xerces can't validate the xml correctly

is there any way to teach xerces to ignore these empty or non-existen 
namespaces in the xml-files like some sort of - if there is nothing or 
some empty namespace use this one instead?

(schema/xml cn be online tested with 
http://www.freeformatter.com/xml-validator-xsd.html)

my current schema

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"; 
attributeFormDefault="unqualified" elementFormDefault="qualified" 
targetNamespace="http://foo.xsd"; xmlns:tns="http://foo.xsd"; >
<xs:simpleType name="hex-integer">
    <xs:restriction base="xs:string">
        <xs:pattern value="0x[0-9a-fA-F]+"/>
    </xs:restriction>
</xs:simpleType>
<xs:element name="TheElements">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="MyElement">
                <xs:complexType>
                    <xs:attribute type="tns:hex-integer" 
name="TheValue" use="required"/>
                </xs:complexType>
            </xs:element>
        </xs:sequence>
    </xs:complexType>
</xs:element>
</xs:schema>

sample #1 - is valid

<?xml version="1.0" encoding="utf-8"?>
<TheElements xmlns="http://foo.xsd";>
  <MyElement TheValue="0x20" />
</TheElements>

sample #2 - is invalid due to namespace miss-use

<?xml version="1.0" encoding="utf-8"?>
<TheElements xmlns="">
  <MyElement TheValue="0x20" />
</TheElements>

sample #3 - is invalid due to namespace miss-use

<?xml version="1.0" encoding="utf-8"?>
<TheElements xmlns="http://foo.xsd";>
  <MyElement xmlns="" TheValue="0x20" />
</TheElements>