The sample provided here throws an error, the default site map provider must be defined in the list
This error can be fix it by the following code.
<configuration>
<!-- other configuration sections -->
<system.web>
<!-- other configuration sections -->
<siteMap enabled="true" defaultProvider="Company1SiteMap">
<providers>
<add
name="Company1SiteMap"
type="System.Web.XmlSiteMapProvider"
siteMapFile="~/Company1/Company1.sitemap" />
<add
name="Company2SiteMap"
type="System.Web.XmlSiteMapProvider"
siteMapFile="~/Company2/Company2.sitemap" />
</providers>
</siteMap>
</system.web>
</configuration>
As you can see you should to define first one of the provider in the list of sitemap name as default.
The other sitemap file are no aveilable as desing time, you to do this programaticaly like for example
sitemapdatasouce1.sitemapprovider="Company2SiteMap" in the load seccion of sitemapdatasoucer object and so on.