In MS3D, in the 'groups' bit, you can select each element of the model. Each one has to have a definition whch is stored in the box tha oens up when you press the 'comment' button

Go into 'groups'

click on the 'comment' button.

Do this for all the parts on the body, and you should see what the pattern is. This defines each part for the model when it is swapping parts over. For a 'body' named ' Body_01 you should see

Body
Body_01
0

IF there was another body part that the game could choose when displaying your warrior, you could call it 'Body_02' and give it a comment oc

Body
Body_02
0

The first part tells it it is a 'torso' and the game knows this is a part of your figure. It then knows it can randomly choose Body_01 or Body_02 for the part named 'body'. If the part does not have this, the game cannot tell what it is or when to display it. This can have odd results.

Most likely, though, the parts you have merged are using completely different materials. If the 'scalp' was mapped to TextureA, and the rest mapped to TextureB, the model may be getting confused as to what material is whiat. Make sure you are using the same texture for the part you are merging as you have on the main model. There is a texture definition , also, in modeldb. Make sure you have the correct texture in there AND fo rthe .normal texture. IF this is not right, you get some VERY odd results....including the one you described. You would never guess a texture could do that...but it can!