W/e. King Zeal can stay dead for all I care. If he was in the way, Zeal probably wouldn't have prospered as much as it did. And if he was still alive, then Schala wouldn't have had to have been Janus' mentor pretty much, or like his one dearest family member who he would search time and space to find again.
Besides that, I always reckoned that Melchior and Belthasar looked after Janus and Schala as children. Belthasar wouldn't have such a longing for Zeal and Schala and all if that wasn't true, and Melchior jumped infront of the gate to save Janus.