this question is.. are any soft canon or soft canon comic books like my fave book called Star Trek: The Next Generation ISSUE #49 The ARMIES of The NIGHT. would any foundry mission based on the books like this one? just a question.
Yeah it gets murky in the world of rights, there is no guarantee that CBS for example owns clearance on the stories in the comics, the individual authors might, and that start just a minor legal minefield there...
Well, the way I see it - and I often work with different IP - is that you should be all right using Krenn - as long as you don't change the character.
This means, if Krenn doesn't get any character development, and nothing happens to him that would matter outside of your story, it counts more as a cameo and nothing more.
You cannot, however, let him do anything major or let things happen to him that would give him psychological trauma. i.e. you can bump into him and talk but you cannot free him from prison or something.
The same thing should be true for all other characters, except that when using one that had a real life actor, you may not use that actor's likeness - that's no problem though as you can't do that anyway.