Elia played in the Bundesliga for HSV in 2011/2012, then he transferred to Juve late August, and played a match against Catania.
Now - He's already played for two teams, right? If we were to sell him in January, he'd have to play for a third team (which isn't allowed).
It hasn't anything to do with CL.
As far as Ziegler goes, he has only been registered for two teams (Juve & Fener), not three.
This is one of the matches Elia played for HSV
http://www.worldfootball.net/spielbericht/bundesliga-2011-2012-borussia-dortmund-hamburger-sv/