** We came up with a workaround! ** Search engines look for a sitemap.xml in your root folder, as does Google. But with Google, you can enter a sitemap at any URL on your domain.
- Upload your desired sitemap (or sitemaps) to Files
- Copy the URL of that file upload
- Create a URL Redirect with whatever path you want (/sitemap/ ?) and point that to the URL of the uploaded file
- Submit the redirect to Google as your sitemap
This worked perfectly for us, with bumped rankings for the level of specificity we got with our tailored sitemap.
@JMont
You still cannot replace the existing sitemap but you can make a strong sitemap that may reduce the impact of any bad URLs added. Or take advantage of those URLs to redirect to good pages on your site, though not sure the impact if you can’t change the canonical URL for the bad URLs inserted.