Making a document link the main document

I've got a method that returns the top level alias path. Maybe this might help.

        /// <summary>
    /// Gets the top level navigation from a URL
    /// </summary>
    /// <param name="URL"></param>
    /// <returns></returns>
    public static string GetParentAlias(string URL)
    {
        // putting a dummy value in so if it cannot get a URL it will return one that doesn't exist and not display any items.
        string ReturnValue = "/unknown";
        // parse out the URL and get only the text between the first / and the second /
        int firstIndex = 0;
        string urlFirstSlashRemoved = URL.Substring(1, URL.Length - 1);
        if (urlFirstSlashRemoved.Length > 0)
        {
        // check for second level page ie: /page1/page2/
        firstIndex = urlFirstSlashRemoved.IndexOf("/");
        if (firstIndex > -1)
        {
            ReturnValue = "/" + URL.Substring(1, firstIndex);
        }
        else
        {
            // parent page
            ReturnValue = URL;
        }
        }
        return ReturnValue;
    }

Regarding the deletion of a node and moving the other up, you'd have to first move the node(s) you want to make "primary" and then delete the other node. Check the APIExamples thats part of your install for code samples.

About moving the documents, if you delete the main node it will also delete all the linked nodes, so that won't work.

As I mentioned you need to move it first, then do the delete of the original parent.