I assume you know that the peace and harmony is soon to end! Pretty soon that dovii pair is going to start causing trouble. The managuense will probably be the first target.
Normally it is safest to keep only one of related species in a tank. Managuense and dovii are closely related and will begin to fight very soon. Also, if the dovii pair breeds, all the fish in the tank will become targets. You might have better results with just one dovii or managuense in that tank.