Hi,
Don't worry. I am a fanatic of the hallmark that's all. usually the hallmarks are on the arm, like on the Hohenzollern knight cross. If it is an Altenburg knight cross you would probably find the following hallmark : EE. So if there is nothing your knight cross is probably from Saxe Coburg Gotha or Saxe Meiningen.
Why I ask that ? If your cross is from Altenburg, like there are less crosses awarded that two others it would be, noteasy, but possible with Lippe rolls, trying to identify this very nice medal bar.
Christophe