Yes, Evil-Merodach ruled before Belshazzar. Evil-Merodach was legitimate heir of Nebuchadnezzar. Nabonidus had him assasinated after only two years on the throne (562-560 BC) and pulled of a palace coup to take the throne. He was NOT a legitimate heir. For this reason, he felt insecure about rivals to the throne. In order to help legitimize his reign he married the daughter of Nebuchadnezzar. His first son was Belshazar. He set up Belshazar as a regent king in Babylon. For thirteen hears Belshazar was the effective ruler of the empire, although there is some question as to how much of a role Nabonidus continued to play. This explains why it is that in Daniel 5 Belshazar offered the person who interpreted the writing on the wall the third place in the kingdom, rather than the second place in the kingdom, as Belshazar held the second place in the kingdom. Evil Merodach is not mentioned in Daniel as none of the visions he had came during the short reign of this son of Nebuchadnezzar.