enewsletter and subscribe to groud when confirmation

Hello WPMU DeV killers,

I have a problem with your enewsletter. I will try to explain what's wrong in my bad english :

I have a main group and a lot of groups with my newsletter. And when a user is subscribing, it automatically subscribes to the main newseltter. And of course I just want he can chooses to subscribe to the multiple groups (group of enewletter).

To do this job ... in the page of confirmation (enewsletter confirmation page) I add this shortcode :

[enewsletter_subscribe show_name="0" show_groups="1" ]

and the problem is this one :
User can choose subgroup only if it is a registred user ... and if it is not, you can see nothing.

And I'm just wondering how can I solve this problem ?

thank you for your help ....