GSDElsa,For instance, this is taken from a post on PBD:
"Fero could produce, imo, reproductive problems in females (small litter sizes, difficulty getting pregnant), missing testicles, missing teeth. Too much nerviness is possible--as in very reactive dogs with low thresholds, sometimes workable and sometimes not. Chewy and hectic grips would come with that."
This is about linebreeding with Fero in there. NOW...don't take that to mean that this breeding is BAD by any means (I have done no research on this myself!), but it gives you some of the CONS of having him in the bloodlines a lot. So now next step for you after you've gathered info like this is to go find info on Josi and Addi and see what you can find.
Sorry to not be all that helpful with actual information. It's a lot of work to find the info out. Perhaps someone who is more knowledgable on the actual lines can chime in rather than just giving you hints on how to get the dirt yourself. Which I realize isn't really all that helpful.
ETA: And again, just want to be clear that I don't think that Fero isn't a good stud (he was!) as I'm looking at a breeding with him in there as well...