The assassin devils are 15'ft apart from each other. Matron mother between them.<br/><br/>Anyways correct assumption there. Also if your dragon uses some spell or other effect to locate them, then your dragon directs mentally which squares they are in. But note they both have nondetection on so CL 29 to locate them with divinations. Also their invisibillity is supernatural and so divinations which dispel or see through invisibillity do not work. But it works only as swift action until end of their present turn but I mention it as they exclusively will start use it when you figure out how they are able to hide in plain sight (yes and they got +35 hide and MS checks and so beatting your lot's spot and listen checks easily).