Steven, Both Nafziger, in "Napoleon's Invasion of Russia" and Otto von Pivka, in "Armies of 1812" have the 7th Polish Lancers joining the 12th Light Cavalry Brigade . Sadly neither gives a date for this , just "joined later" is all either has to say. "Armies of 1812" gives the Colonel as Klicki when listing the regiment under 12th Light Cavalry Brigade but gives the name as Zawadzki when listing it under 4th (Polish) Light Cavalry Division.