Hey everyone, I wanted to create an armor similar to the one from the cancelled Gothic sequel

It obviously doesn't work in game and crashes (access violation, will update with logs later).
Steps done:
# Changed appearance of existing armor
# Merged two skulls (skull.3ds) in the scene
# They still are two different entities, named Skull1 and 2 (with the zm_ prefix)
# Connected them to the main body ( zm_Sld_Tm)
# Compiled
# Access Violation error
# Restart game
# Shows armor without skulls, and different texture
I have a couple questions:
#1: How do I join the skulls to the main armor, specifically how do I rig them onto a bone? I fear some of the issues are that the skulls aren't exactly connected to the armature, but I'm a noob with Blender and couldn't find anything helpful on this site.
#2: I have added to the normal guard armor two skulls, which are .3ds files. Does that compromise the compiling in-game? They're two different formats after all.
I'll upload the files shortly, so you can have a look at them yourselves.
EDIT:
https://mega.nz/#!FUBHSLiA!uu8V0POqv7llN5VzRcFB-THn_V3-2IeKmy7_cCcRbQM