Thanks for your reply..
so I only need to use..
define( ‘WP_REDIS_DATABASE’, ‘1’ ); ???
is this the correct syntax as it still appears in wordpress admin as database 0
I tried just using
define( ‘WP_CACHE_KEY_SALT’, ‘site1 );
define( ‘WP_REDIS_SELECTIVE_FLUSH’, true);
and this causes pages and data to be shared between the 2 sites?