Raising 2 additional pets plus your base pet in a group with 2 necros and a couple more pet classes would mean 14-15 entties on screen for just the group alone, plus however many mobs are active. The entire reason Devs removed several pet classes is because of the confusing visual overload situations like this cause.
I have a similar suggestion in this thread - you're still limited to one pet mob, but raising a corpse would give extra benefits.