don't forget it also depends on the size of the extra moon
I also need to do some more work on the languages that are spoken
If their masses are similar enough to rule out the L4 and L5 points, you could lock them in a different orbital resonance, like how three of Jupiter's moons (Io, Ganymede, and Europa, I think?) are in a 1:2:4 resonance.
Or if the moons are small compared to the planet and the planet itself is fairly large, you could just have one orbit close to the planet and the other much farther away, and the orbits would probably be stable enough.