Vastly improving the unsubscribe functionality -- Feature Request

I want to use one Mautic install/list to send newsletters for several blogs and brands (each of which I made a Segment for). When someone clicks “unsubscribe” it needs to unsubscribe them ONLY from the brand/blog (Segment) that particular newsletter was about – not from ALL of the brand/blog newsletters.

It would be great to be able to select the SEGMENT for the unsubscribe link, while making the email, so it only unsubscribes them from that one segment.

In other words:

I want to send emails to my entire list that are associated with particular Segments. For example, Brand A is Segment A and Brand B is Segment B – I want to be able to put all my contacts in both segments, then when I send a newsletter, specify which segment the newsletter is attached to. Then if a contact unsubscribes from a Segment A newsletter, it only unsubscribes them from Segment A, and not Segment B.

So in the edit contact view, I would need to be able to be able to use checkboxes to add them to multiple Segments. It would also be great to be able to easily assign all my contacts to segments in some efficient/bulk way, since I have 300,000 contacts.