How to combine sitemap extensions
  Sitemap extensions are a great way to tell Google about the different kinds of content and
  their metadata that you're using on your site. Often the content on your pages may fit into
  multiple kinds of extensions; for example, you might be publishing news articles that embed
  images and videos. Additionally, your pages may be localized as well, which might mean that
  you could add hreflang annotations for your localized pages.
Namespaces
  For each sitemap extension that you want to use in a sitemap you need to specify the
  respective namespace that declares the tags the extension supports. This is done with the
  xmlns attribute of the urlset tag. The namespaces for the sitemap
  extensions Google supports are:
| Extension tags and their namespace definitions | |
|---|---|
| image: | http://www.google.com/schemas/sitemap-image/1.1 | 
| news: | http://www.google.com/schemas/sitemap-news/0.9 | 
| video: | http://www.google.com/schemas/sitemap-video/1.1 | 
| xhtml:(forhreflang) | http://www.w3.org/1999/xhtml | 
Declaring multiple namespaces
  To declare multiple namespaces, add the respective namespace references to your sitemap as
  described in the documentation of the respective extensions. Here's an example that shows how
  to add the news, video, and xhtml (for hreflang) extensions to a sitemap:
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
           xmlns:news="http://www.google.com/schemas/sitemap-news/0.9"
           xmlns:video="http://www.google.com/schemas/sitemap-video/1.1"
           xmlns:xhtml="http://www.w3.org/1999/xhtml">
  <url>
<!-- rest of the sitemap -->Combining sitemap extensions
Once you declared the namespaces, follow the implementation details from the respective sitemap extension documentation you're going to use.
  To combine extensions, add the tags from whatever sitemap extensions you're using, one after the
  other, to the appropriate <url> tag, as described in each sitemap extension's
  documentation.
  For example, to add news, video, and xhtml (hreflang) extensions to a sitemap:
<?xml version="1.0" encoding="UTF-8"?> <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:news="http://www.google.com/schemas/sitemap-news/0.9" xmlns:video="http://www.google.com/schemas/sitemap-video/1.1" xmlns:xhtml="http://www.w3.org/1999/xhtml"> <url> <loc>https://www.example.com/english/page.html</loc> <!-- Starting with the news extension tags --> <news:news> <news:publication> <news:name>The Example Times</news:name> <news:language>en</news:language> </news:publication> <news:publication_date>2008-12-23</news:publication_date> <news:title>Companies A, B in Merger Talks</news:title> </news:news> <!-- Next we add video extension tags --> <video:video> <video:thumbnail_loc>https://www.example.com/thumbs/123.jpg</video:thumbnail_loc> <video:title>Lizzi is painting the wall</video:title> <video:description> Gary is watching the paint dry on the wall Lizzi painted. </video:description> <video:player_loc> https://player.example.com/video/987654321 </video:player_loc> </video:video> <!-- And finally the xhtml tags for hreflang --> <xhtml:link rel="alternate" hreflang="de" href="https://www.example.de/deutsch/page.html"/> <xhtml:link rel="alternate" hreflang="de-ch" href="https://www.example.de/schweiz-deutsch/page.html"/> <xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/english/page.html"/> </url> <!-- Add more <url> tags -->
  The order of the extension in the sitemap is irrelevant after the <loc>
  tag. Keep in mind the
  general sitemap best practices,
  especially the file size limits. Combining sitemap extensions increases the file size of your
  sitemap significantly.
Troubleshooting sitemaps
If you're having trouble with your sitemap, you can investigate the errors with Google Search Console. See Search Console's sitemaps troubleshooting guide for help.