Subfolder Multisite : optional www subdomain

I use the plugin “WordPress MU Domain Mapping” for mapping domains to subfoldered-subsites. Works well (even though it hasn’t been updated in 2 years), once you closely follow the instructions. Available here: https://wordpress.org/plugins/wordpress-mu-domain-mapping/ . (Although, on retrospect, this may not entirely be the answer to the OP’s question; I may have misunderstood his intent.)

Add custom user fields in Multisite USERS page

It depends on how these functions are being set up. Most likely right now these are set in a theme file somewhere. In that case, they will only run for the sites that have that theme enabled. I have not tried it, but I believe if you move the code that accomplishes your goal into … Read more

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