If I understood correctly. You can open sitemap.xml in notepad/textedit or your favorite editor and add/remove/adjust things as you like...
the following is the format for new items, adjust things accordingly....
<loc>[URL - w/ http://.....]</loc>
<changefreq>[FREQUENCY - weekly, daily, yearly,never]</changefreq>
<priority>[VALUE 0.0 - 1.0]</priority>
Make sure that your <url> sets are inside the <urlset> tags.