It's pretty easy for npcs:Just add them to your CreatureModelData.dbc and CreatureDisplayInfo.dbc with Taliis.You basically only have to copy some entries and then change the model path and id. To add new Modelpaths you have to add new strings in Taliis.Documentation on the dbc files are in the wiki.The entry in the CreatureDisplayInfo is the id you can spawn morph into them. And also the id you have to use in your db to assign them to an npc/mob.Edit:They go in the creature folder unless you want to make them playable races btw. That's even true for shapeshifted forms. I don't think it makes a difference though. It's just how blizz handled it.