Inspect group channel - see what track are routed to one

Hi,
How do I do it? Choosing a group track and seeing the tracks that was previously routed to it.

Edit:
Found it but got a different question.

How can I link another track to an existing group track from the mixer screen? I mean, is there an option to do it to multiple tracks? Not going one by one and changing from the following place in the photo
image

Have a look…

and

Thanks!