Multi-Domain XML Sitemaps

[SidFeyDesigns]

How would one handle multi-domain xml sitemaps using the 1st option when setting up multi-domain: Sell a Subset of Your Catalog From a New Domain.

How does it work to have 2 different sitemaps (primarysitemap.xml and secondarysitemap.xml) be in the root while still only showing up for the correct domain?

Ex:
primary-domain .com/ primary-sitemap.xml shows up for primary-domain .com only and not secondary-domain .com

secondary-domain.com/ secondary-sitemap.xml shows up for secondary-domain .com only and not primary-domain .com

[SidFeyDesigns]

Also, how are robots.txt files handled?

[SidFeyDesigns]

I think I figured it out for sitemaps.xml, robots.txt, and also favicon.ico files.

First I added secondary domain versions of each file to the root directory and then added some rewrite conditions and rules in the .htaccess file right after ### End - Miva Merchant URI Management.

# rewrite robots_sd.txt for secondary-domain.com
RewriteCond %{HTTP_HOST} ^(.*)?secondary-domain(\.com)
RewriteRule ^robots\.txt$ robots_sd.txt [L,NS]

# rewrite favicon_sd.ico for secondary-domain.com
RewriteCond %{HTTP_HOST} ^(.*)?secondary-domain(\.com)
RewriteRule ^favicon\.ico$ favicon_sd.ico [L,NS]


# redirect robots_sd.txt for primary-domain.com
RewriteCond %{HTTP_HOST} ^(.*)?primary-domain(\.com)
RewriteRule ^robots_sd.txt https://www.primary-domain.com/robots.txt [R=301,L,NE,NC]

# redirect favicon_sd.ico for primary-domain.com
RewriteCond %{HTTP_HOST} ^(.*)?primary-domain(\.com)
RewriteRule ^favicon_sd.ico https://www.primary-domain.com/favicon.ico [R=301,L,NE,NC]


# redirect sitemap_sd.xml for primary-domain.com
RewriteCond %{HTTP_HOST} ^(.*)?primary-domain(\.com)
RewriteRule ^sitemap_sd.xml https://www.primary-domain.com/sitemap.xml [R=301,L,NE,NC]

# redirect sitemap.xml for secondary-domain.com
RewriteCond %{HTTP_HOST} ^(.*)?secondary-domain(\.com)
RewriteRule ^sitemap.xml https://www.secondary-domain.com/sitemap_sd.xml [R=301,L,NE,NC]

For the sitemaps/robot.txt files I of course made sure everything matched Google Search Console & Bing Webmaster Tools.


The only question I have is:
Is it necessary to have the redirects in red above for the robots_sd.txt and favicon_sd.ico?

Thanks