Typically, you will need to edit the GN4.XSD and TARK4.XSD schemas.
You have two choices:
1.To keep the same schema file names, and to put schemas in a different set of folders, e.g. CONFIGXXX, as explained in Make a copy of configuration folders.
2.Rename copies, prefixing them with the site acronym, e.g. LW. So there will be LWGN4.XSD and LWTARK4.XSD files. In that case, you need also to rename includes in the GN4.XSD files, e.g. as:
<xs:include schemaLocation="LWTark4Include.xsd">
<xs:annotation>
<xs:documentation>Include Tark4 object types</xs:documentation>
</xs:annotation>
</xs:include>