I have the following example page structure:
If I call Server.Execute(\"Script.aspx\")
from Webpa
Since Server.Execute runs the new page with the same context as the original page, all the properties of Request should still reflect the original request to Webpage.aspx (except for CurrentExecutionFilePath, which hopefully contains "/Script.aspx"). Request.Path should contain "/Webpage.aspx", while Request.Url will give the full Uri object if you need to see the domain or querystring.
You can also add values to Context.Items before calling Server.Execute and read them in Script.aspx