Multi Site installs on sub-domains

I'm trying to set-up multiple Multi Site installs on one domain using sub-domains and want each multisite to use sub-domains not sub-directories, there is an existing Multi Site installed on the root currently that I hope to leave as is.

One source says not possible but a few sources infer possible. I think these are the steps but a few I'm fuzzy on:

1. Create sub-domains and corresponding wildcards in CPanel, one for each multisite install.

2. Upload and install regular WordPress in each sub-domain

3. Add this to my wp-config.php in each sub-domain and in the root Multi Site
define('ADMIN_COOKIE_PATH', '/');
define('COOKIE_DOMAIN', '');
define('COOKIEPATH', '');
define('SITECOOKIEPATH', '');

/* Multisite */
define( 'WP_ALLOW_MULTISITE', true );

4. add a .htaccess file into each sub-domain

5. enable Network, choose sub-domains and replace existing WP lines with these new ones in .htaccess

6. On MultiSite install at root level, change salts

7. .htaccess - not sure but a rule to allow sub-domains to pass through the root htaccess to sub-domain htaccess, and assume same htaccess rules in each sub-domain as root... not sure

Help feedback please!
Thanks,
Louis