VtM:Bloodlines models

I know this game is pretty old but I still love it and still play around with skins for the game. To get some variety I’ve tried making skirts shorter or invisible and adjusting hemlines, that sort of thing. What gets me is that I can take a model and grab clumps of her hair (that are not attached to her body) and move them around and I will see the effect in the game but on the same model I’ll try to make the skirt shorter and the changes won’t show up in game.

I’m new to blender basics though I’ve played with it to see the models before I put them in game. I can import models and export them but I’m confused as to why some changes would show up and others wouldn’t. I’m not going to spend a lot of time on this but I was just wondering if anyone had an idea of why its doing this.

It uses Valve’s Source engine same as Half Life 2 but I know that doesn’t mean what can be done in one game can be done in another but would experimenting with another game help me bring skills over to this one? I just figured that if I could make changes to one part of a model then I should be able to do it to other parts of the same model. Am I wrong? Are there different parts of the models that have properties that make them different than other parts? The obvious is hair and garments that move with a character’s actions and others that don’t. Could this be the issue?

I know the game is old but I still love to play it and now I want to play it with characters I’ve modified. Any thoughts or suggestions would be appreciated!