The kids are so cute！(^_^)

@panadero since your "Public" and "Private" groups are in fact meta categories, there is no default way to set different visibility values to them. However, you can control the visibility of the posts in the private group by keeping them as Community instead of Public, that way they will be visible only for logged-in users.

In addition to that, you may apply these changes to do not display empty categories in the front page. If a category contents only non-Public status posts, it will be empty for not logged in visitors (see screenshot).

https://github.com/mgsolipa/b2evolution/commit/7836f006b1107cdbcaf539f421d65d635f33b851

This is the modified raw skins/bootstrap_forums_skin/_front.disp.php file for your current version: https://github.com/mgsolipa/b2evolution/blob/7836f006b1107cdbcaf539f421d65d635f33b851/skins/bootstrap_forums_skin/_front.disp.php

Manuel,
Thank you. This is what I was looking for. I will compare the files to see what changes you made.
I will comment back later after I play with it a bit.
David

Ok, this is just what I needed. Thank you so much.
I see now how to make the necessary changes to permissions, and can move ahead with the project.
Playing a bit, I see that I can go the next level, and hide further groups from users depending on their level or group id.
Cheers!
David

Another approach is to make several forum collections which makes it easier to show/hide some of them completely to certain user groups.