A client of mine wants to switch their single site installation and make it a multi-site one so that they can run an online store on a sub-domain while keeping their existing site on the primary domain.
I’ve Googled all morning but all I can find is ways to import a single site into an already existing multi-site installation whereas what I need to do is convert a single to a multi.
Is this possible?
Have you checked out Create A Network on the codex? Essentially:
define( 'WP_ALLOW_MULTISITE', true );to yourwp-config.php