Wouldn't that depend on the exact size of the moons? :s Does your simulator allow you to put in precise measurements? Can I borrow you to test my moon issues? :P
The easiest way is to make the submoon orbit the larger moon. If it's the smaller moon, well let's just say that the submoon would be more like an asteroid. And it would be hard to see it from the planet (I guess).I know it's possible but I haven't been into the details. I bought a astrophysic simulator called Universe sandbox on Steam and it worked. It's possible to get arround this n body problem but Binary star systems are much more complicated...
Yeah... I start with more like.. a photograph of the area in my head. :/ I haven't even been successful with mapping a small region yet, lol.
I already saw your map on another topic... So far, it seems fine to me. I have to admit I have a problem when it comes to world construction. I started with a region with no idea of the surrounding. Yet I find myself ''forced'' to fill the map because things like climates and plates does not make much sense if the world is empty.