I have two live subdomains on a URL, let's call them sd1.mysite.com and sd2.mysite.com. I am looking to turn mysite.com into a Multisite environment, with both those subdomains being apart of it.

My question is, whilst I expect moving the files into the relevant Multisite folders to be fairly straightforward, is there anything special that needs to be done with the databases or are there any settings I may need to be aware of?


4 Answers 4


Assuming sd1.mysite.com and sd2.mysite.com are single WordPress installs.

You can create mysite.com as a WordPress Multisite, you can then export the posts, users, etc and reimport to the new multisite version of sd1 or sd2 using: https://en-ca.wordpress.org/plugins/wordpress-importer/

You will need to include the themes, plugins as well in the new multisite install.

If sd1.mysite.com and sd2.mysite.com are not single WordPress installs and just subdomains, you just need to point the subdomains to mysite.com IP address.


Export the posts and import using the importer listed above. The sd1 and sd2 databases will no longer be needed as mysite.com DB now holds everything.

  • 1
    Hi @liam-stewart, thanks for the response. The sites sd1.mysite.com and sd2.mysite.com are subdomains of mysite.com and are set up as WordPress sites. What happened was the original developer set up these sites as subdomains without knowing what Multisite is. My plan is to enable Multisite on mysite.com (because more subdomains are needed) and include sd1 and sd2 into that new Multisite setup. So, transferring content/themes/plugins over won't be an issue, but how would the databases of sd1 and sd2 need any special work? Dec 28, 2018 at 17:03
  • @damienoneill2001 Edited my answer Dec 28, 2018 at 17:16
  • Thanks for that, however, I think you may be missing what I want to do. I am not trying to move the content from sd1 and sd2 into mysite.com's database. Those two sites will remain as subdomains but I am trying to include them into the new Multisite setup I am trying to create. Ultimately, there will be hundreds of sites on this new Multisite set up and sd1 and sd2 will be the first two. I am trying to determine if there is anything special that needs to be done to convert them from their current non-Multisite set up to what will be the new set up. Dec 28, 2018 at 18:13
  • I follow the ask - I want you to include the content in the multisite version of sd1 and sd2. You can't merge the databases, so you will need to create the subdomain sites via mysite.com multisite and then import the content from the previous version. Dec 28, 2018 at 18:15
  • Oh ok, so the two sub domains need to be recreated in the multisite version. Then, from there, all the content needs to be transferred into the new versions of the subdomains? Can I ask though, if those subdomains already exist, how can they be recreated as new sites. Surely the domain name needs to change for that to happen which is not something I want to do. Dec 28, 2018 at 19:06

I had pretty good experiences using WP-CLI and the WP-CLI plugin MU-Migration. You most certainly have to install the latter, depending on your environment the former too, consult the documentation on that.

Afterwards exporting can look like:

wp mu-migration export all site.zip --plugins --themes --uploads

And importing:

wp mu-migration import all site.zip

This is the most basic rundown, more parameters are available. The documentation, linked above, is informative and straightforward. Just to clarify, this works for migrating a single site to a multisite setup too, see the following article for this scenario and a general rundown, the article will be helpful to get started.

Obviously backups are mandatory for any crucial operation, so better be safe than sorry.

In my opinion those are great tools, which can make your life much easier, maybe you want to take a look at them.

  • Hi @Nicolai, thanks for the message. So with this process, I will be able to take what is an already existing sub domain and import it into a MU setup, but leave all the URLs the exact same. Ultimately, sd1.mysite.com and sd2.mysite.com need to remain as sd1.mysite.com and sd2.mysite.com, just be part of the MU network now? That is the bit that confuses me. How do I set up the URL when that URL already exists? Dec 31, 2018 at 9:56
  • @damienoneill2001 Yes, you will be able to migrate the subdomains into a MU setup. Please read the documentation, and this scenario is described in the linked article. There is a difference between migrating the sites between WordPress installations – multisite or not, or subdomain or not is just a technicality here –, and the server setup for the subdomain. Right now your subdomains are most likely pointing to the directory of their single site installation. At one point or another you either have to implement a wildcard subdomain … Dec 31, 2018 at 12:16
  • … for your multisite or, if the former is not possible, set up the single subdomains for use with your multisite installation. There is plenty of information out there, how to set up a multisite installation with subdomains, just find it. Generally speaking, migrate, export and import data, the domains in question, then change, as outlined above, the server setup for the migrated domains. Dec 31, 2018 at 12:17
  • Hi @Nicolai, whilst I do appreciate your answer and I would have liked to award you with the bounty, I am not aware myself of how to work with WP-CLI and whilst it might make the process overall easier, it is not something I would be pursuing myself. Jan 4, 2019 at 16:04
  • @damienoneill2001 No worries. Unfortunately I didn't have the time to get deeper into it. If not for you, this might be helpful someone else. Jan 4, 2019 at 20:26

There were two articles about how to migrate Single WP sites into MultiSite and Migrate Subdomains into MultiSite, which helped me much. The whole point is that if you are not going to use migrator plugins, then you have to do very accurate manual modifications with phpMyAdmin. If you are not familiar with that (or don't have anyone to work with that), then you can't simply do the process, and you will need a help of migration plugins (there exists commercial plugins, which do exactly what you want), or hire a programmer to do that.

  • Thank you for this answer. The articles you provided are what I was looking for for this process, appreciate the help. Jan 4, 2019 at 16:03
  • @damienoneill2001 thank you, they have helped me too many times.
    – T.Todua
    Jan 4, 2019 at 16:03

Have you checked to ensure all your current plugins work in a multi-site setup? The last multi-site setup I worked on ran into a number of limitations because certain plugins didn't work multi-site the way you expect them to. We ended up having some plugins on the network, and others that had to be individually installed on each site in the network. Not a biggie, but when you multiply that hundreds of times, it can turn into a real hassle!

Adding to that, even plugins that do work multi-site can require basic setup steps repeated on each site in the network, so try and identify plugins that allow you to centralise as much as possible.

Also, this is an obvious one, but double-check, and then triple-check that you have the first two perfectly setup, before you clone them to the other sites in the network, because any manual functionality or setup can turn into a major chore.

  • 1
    Hi, thanks for the tips, I'll take them on board obviously. Dec 31, 2018 at 10:29

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