Combine multiple sphinx documentation sites

I would like to combine multiple sphinx generated documentation sites into a single location (site). I dont want to replicate the work, but just want to index/search it from a central location.

Requirements:

1. Searchable documentation across all sites from main site
2. Searched link takes you to target site/location
3. Link to all other sites (should be easy enough)

MainSite

• Site 1
• Site 2
• Site n

I was thinking of somehow combining the index databases from the various sites, but did not know if that was possible. I am finding very little information about doing this.

I had considered using a google search that specifically targets the desired sites, but would like to keep the Sphinx look and ease of use. Is this even possible? Any ideas how? Thanks