So in this video http://www.youtube.com/watch?v=TAih_jr233I&feature=g-all-s&context=G2db73b3FAAAAAAAAAAA it describes how to make enemy npcs have followers, the example given was a necro having skellies follow him around. However, when I try to do this, the skellies attack the the person they're supposed to follow. The only difference between what I am doing and the video is that the necro in my mod is a unique NPC and not a lvl mob. Maybe it's some sort of faction issue, IDK. Any ideas would be appreciated!

Maybe put them in the same faction, or create an ally relation between the two of them?

how do you create an ally relation?

is there a way to put every monster in my dungeon on the same faction without manually adding them to the same faction, for the purpose of them not attacking one another?

Without scripting i would say no, best to do it while your making the dungeon or what ever it is, i generally make a unique version of the creatures i will use that way i can add them all to the same faction without effecting any vanilla creatures.