Docker Linking

I read this post about docker linking in the unRAID forums. 

Maybe this is a dumb question but.....

Can you link two containers? 

1. I have linked Sonarr and NZBGet and it works fine - score!
2. I also use "Hydra" and would like to link Sonarr and Hydra (at least I think this would be nice?)

I tried both "--link hydra:hydra --link NZBGet:nzbget" and "--link NZBGet:nzbget hydra:hydra " but neither seems to work?

And perhaps you are only meant to link one container to one container? 

Thanks!