Albanians against the Ottomans
I have read here and also heard from many people that the albanians were also fighting against the ottomans.
In the belligerents you should add albania. Many orthodox albanians were forced to flee or convert to be muslim and it is important that you clarify this in the article.
http://www.albanian.com/v4/showthread.php?t=8470

   An anti-Ottoman coalition of Hungarians, Bulgarians, Romanians, Poles, Serbs and ALBANIANS headed by the Serbian   prince Lazar fought a Turkish army twice its size on the plain of Kosova near Pristine on 15 June 1389. 
   Troops of  Gjergj II Balsha of Shkodra and of Theodore Korona Muzaka of Berat participated. 
   Even though an Albanian named Milosh Kopiliq penetrated to the Sultanâ€™s tent and assassinated Amurat I, the Turks succeeded in destroying the Balkan coalition.