Need help with another thing..

We were able to make it so that the bookmark doesn't go away when more than one checkbox acting on the same bookmark is checked. Now, how do we make it so that a bookmark only appears when two or more bookmark is checked?

Adding on to my example above about products and requirements:

I have an additional feature called CheckBox3 that I can add to products CheckBox1 and/or CheckBox2. I have an additional requirement that comes with CheckBox3 called Bookmark2. The thing is that Bookmark2 should only appear when Checkbox3 is checked AND when CheckBox1 and/or CheckBox2 is checked. Everything else that we did still need to apply as well..