Hi Guys,
Sorry to jump in here, but I may have a work around for Holger.
When you create the subportal, in the provided example, 'testsub' (accessed via intranet.acme.com/testsub), DNN will create the testsub sub directory (e.g. \webroot\mydnn\testsub) and create a new Default.aspx there. This page's only goal is to do the direct back to the \webroot\mydnn\Default.aspx page.
You could try modifying the \webroot\mydnn\testsub\Default.aspx adding the additional parameters.
E.g. Update the following line (35)
FROM:
DomainName = ServerPath & "Default.aspx?alias=" & DomainName
TO:
DomainName = ServerPath & "Default.aspx?alias=" & DomainName & Me.Page.Request.Url.Query.Replace("?", "&")
I have not tried this so I'm not 100% sure it will work. The only other draw back is that you will need to make the change to every sub portals Default.aspx manually.
I hope that helps.
Michael