регламент ЛЕ на сезон 2010/201118.18
One player from the above quota of three who has played UEFA club competition matches for another competing club in the current season may exceptionally be registered provided that the player has not been fielded: − in the same competition for another club; or
− for another club that is currently in the same competition.
Furthermore, if the player’s new club is playing in the UEFA Europa League, his former club must not have played in the UEFA Europa League at any point in the current season.
короче говоря, игрок который дозаявляется не должен быть заигран за другую командую, принимающую/принимавшую участие в этом же турнире .........