That’s what I thought, you’re probably going to have to a PHP output filter to send the value in the field into a PHP function to return the value in the format you’re wanting.
ie, if you pass {@related} to a PHP function, it will pass that as an array, so you could do {@related,join_with_commas}
and put the following function in your functions.php (or somewhere in your own plugin, etc.):
function join_with_commas ( $array ) {
return implode( ",",$array );
}
implode
will join the values of the array with the character intended. Since the relationship magic tag stores the ID’s of the connected post types, this _should_ work, but you might want to test yourself. I’m not by any means a PHP Developer ??