Dixi Theme - Adding Subscribers

I hope you can help me, I have been trying to do something with the Dixi Theme.

I have a multisite with Buddypress. I have the Dixi theme on a sub domain. So when you visit this site there is the welcome message in the sidebar with the avatar, once you are logged into the main site. If you are not logged in it gives you the option to create an account. So all that is great.

What I want to do is, if the visitor is a member of the main site, it checks if they are a member of the current blog (I thought: is_blog_user() ), if they are, do nothing, otherwise I want to display a button that they can click to become a subscriber (add_user_to_blog($blog_id, $current_user->ID, "subscriber") I have the button, and I put an if statement in the profile.php file right under where it calls the avatar, but it didn't work. Could you suggest what I could try in this situation?

Also, this isn't related to the Dixi Theme, but I have used the supporter badge file, to create a file to show a badge if the member is a subscriber to the above site. So I replaced if ( is_supporter() with If (is_blog_user($blog_id = 2)), but it shows the badge even if they are not a user of blog 2. What could I try here?

Lastly, a very minor thing, but where would I find this statement "Sorry, the comment form is closed at this time." to remove it from pages in the Dixi Theme.

I hope you can help with this, I have been trying now for ages, with no success.

Thanks, Fondeli.