WordPress Multisite Dilemma!

Cannot guarantee, but I believe there will be zero SEO impact. The new subdomain site inside Multisite will be an exact clone of the former standalone subdomain. Same theme, plugins, content, canonical URLs.

Steps to take:

  1. the standalone subdomains cannot reside in the same folder where Multisite will run, e.g., something like /home/user/public_subdomains/ instead of /home/user/public_html/
  2. change one working subdomain and test, and then change all
  3. set up Multisite in the main site with Subdomains configuration
  4. enable Wildcard subdomains for the main site: *.example.com. And this is why currently running subdomains won’t work if left in public_html.
  5. migrate one subdomain and test, and then proceed to the rest

Now, step 5 is the key. It can be done manually or using a plugin. I don’t have it bookmarked, but I know @Ipstenu did explain this in WordPress forums. Also, I’ve seen a few nice plugin recommendations over there too. The one I use is BackupBuddy, and although Multisite support is still marked as beta, it performs reasonably well extracting and inserting sites in MS.