Can't make my mob attack other specific mobs in a procedure

hey, i am trying to make a smart zombie, so far i made it jump over high blocks and very hard to kill but the problem is that i am trying to make them heal by killing sheeps but i can't seem to make them do that cause there is nothing about targeting mobs, i saw people talk about making it target a specific mob in ''ai and goals'' but i don't want to do that because there i wouldn't be able to make them heal after killing sheeps. please help. thanks in advance