I think that the immotiles that compete with each other were not created by others, they were the last generation of creatures that give birth. There might be 7000 of them to begin with, then they kill each other off. To survive and conquer, the immotiles must have large armies of motiles. At first, the immotile would have whatever amount of motiles, but as it expands, his grip would become looser. Imagine if you constantly grew new toes, and had to wiggle them all in specific patterns. Eventually, you couldn't control all your toes. It would be the same for an immotile.
The second immotile would be almost like a second brain for a while. Then, when it develops, it is weaker then the one that created it, like a high level motile. You'll notice that most of the immotiles are called MorningLightMountain35, or 6735. They are the minions of the original MorningLightMountain. If the original is killed, the minion immotiles become sentient, taking their own names and their own motiles.
The first immotile suppresses their intelligence. Each immotile owns their own motiles, and the one that created them, rules them. Really, as long as the original is alive, it has nothing to worry about. If it's dead, then it also doesn't need to worry about it. When it first creates another immotile, it has the extra mental capacity provided by the developing immotile.
Then, when it becomes sentient, the original could just control it, and it would control the motiles. It's like the difference between commanding your army, and commanding the guy who commands your army.