No, that's not the case Crimson. In the situation you're describing, the added monsters instantly relink, this is present in BCNMs and whatnot. The situation that this covers is when you've done nothing to gain enmity on a mob, but your party/alliance has aggroed something, you release, and the mobs come after you. Like people have said, this is present in supertanking fights. This includes things like einherjar (if you're mass pulling mobs), Qilin, etc. The point is that currently, you're releasing your pet, which is causing mobs to attack you.