England face losing Manchester City's Nmecha brothers.
Lukas, 20, currently on-loan at Preston and Felix, 18, have both been capped by England at youth level.
However, Lukas has been named in Stefan Kuntz's Germany U21 squad this past week, while Felix has played for both nations.
Born in Hamburg as the sons of German and Nigerian parents, the Nmecha family emigrated to England in 2007. Accordingly, the two are eligible to play for Germany, England and Nigeria.
Felix is now with England U19, though has also played for Germany U18.