[Edratman]

I place new monsters from mods in map files all the time without problems and I only use unit ID number. I place them both as starting commanders and sole units, like a scout or mage. But you actually place them in a province, which you set as your starting province.

I've forgotten to specify ownership of the province that I've set commanders in. They then become indies.

You should be able to place your monster as a third commander in your starting castle using a map edit #commander. To make it one of the two starting commanders you have to change the #startcom command in the dm file.