Ring wraiths vs. Balrogs

[obloquy]

The actual entry:

c. 2480 Orcs begin to make secret strongholds in the Misty Mountains so as to bar all the passes into Eriador. Sauron begins to people Moria with his creatures.

Notice that the orcs moving into the Misty Mountains, and Sauron peopling Moria with his creatures are separate events. The Misty Mountain orcs are a different breed than those troops of Sauron that we read about in LotR. What "creatures" could mean besides orcs, I don't know, but I think the use of that word is significant. Even if Sauron was behind the populating of Moria with orcs, I don't think it's reasonable to consider them Sauron's 'troops' at the time covered in LotR.

Sauron mut have at least known about the existance of the Balrog. The Balrog and Sauron must have at least had an understanding.

I don't see how this is necessary. Why do you say so? The Balrog appeared in Moria 500 years before Sauron is said to have 'peopled Moria with his creatures', so we know the Balrog wasn't one of the creatures. What reason do we have to believe that Sauron knew of the Balrog, or set up some arrangement with it?