Yes, you only have one set of plugins and themes with multisite and you can create a new subsite with just a couple of clicks at any time which is a handy feature. The other benefit is, you only have one set of WordPress files and one database instead of two or more. Multisite just adds a few database tables to your existing database. Keeps things smaller on hosting. Not all plugins are multisite friendly so if you have some favorites, you might want to check to see if they’re compatible. Your first stop might want to be this.
https://codex.www.ads-software.com/Before_You_Create_A_Network
If it’s still something you want to do them continue with below.
NOTE* I just read that you can trick wp by changing all of your post/page dates to be less than 30 days old and then activating multisite and it will give you subfolder option as well as subdomain. So try that and it might negate steps 3 and 4 below.
What you’ll have to do is set it up as subdomain and then change it to subfolder. You’ll need to be able to access and edit the wp-congif.php and .htaccess files at the root of your site so make sure you can do that first. Would be public_html or www on your server/hosting. You would use ftp or cpanel most likely. For cpanel/file manager, you may have to turn on something to be able to see .htacces. Anything that starts with a dot is a hidden file. You might have to search your hosting’s help pages for “show hidden files in file manager” or some such. Same with your ftp program.
Here’s a reference page, https://codex.www.ads-software.com/Create_A_Network
1) Activate multisite
Open up wp-config.php and add this line above where it says /* That’s all, stop editing! Happy blogging. */. If it doesn’t say that anywhere, then add the line somewhere above the first line that begins with require or include:
/* Multisite */
define( 'WP_ALLOW_MULTISITE', true );
2) Set Up Multisite
In admin area, go to Tools>Network Setup (this is where you would be given the choice for subdomain or subfolder on a fresh site less than 30 days old. If changing the post/page dates didn’t give you subdomain option here, just go with subdomain and follow the instructions given)
I think a lot of people get screwed up right here because most instructions aren’t clear.
# BEGIN WordPesss
<IfModule mod_rewrite.c>
THIS IS WHERE YOU PASTE THE HTACCESS STUFF. IN BETWEEN THE IfModule tags.
</IfModule>
# END WordPress
I think some people end up pasting over the IfModule tags. Some .htaccess files can be loaded with stuff so just look for the WordPress section.
3) Change it to Subfolder Part 1;
Now you have multisite but it’s subdomain because it was the only choice. Now we can change it. Go back to wp-config.php and change
define( ‘SUBDOMAIN_INSTALL’, true );
to
define( ‘SUBDOMAIN_INSTALL’, false );
4) Change it to Subfolder Part 2;
In network admin, go to Network>Network Setup and you’ll see the stuff to paste into your .htaccess file but it will be different now.
(You can double check/compare here. Look at posts 15 and 16. https://www.ads-software.com/support/topic/will-there-be-a-fix-for-old-wordpress-installs-for-multisite-functionality)
It will be what you need for subdomain. Paste that over what you pasted in step 2) between the IfModule tags.
That’s it
