Having trouble BPS swapping

[GM]

When I tried to change the female tourist to the Hutz mother and load Unusual Suspects the game crashed and the following sign popped up "Some files extracted from dev-gmc.rar were modified or new files were created

Do you wish to put them to the archive?"

Let me also state that this is a torrent version of the game. I've been dying to try the BPS mod and another mod which worked just fine, though I can't find my GM cd anywhere and the steam version hasn't been working.

I changed the BPS files, deleted the original and renamed it CV_Mother. So according to the forms I'm doing everything right. So what am I doing wrong?

[Nemesis]

First of all: NEVER delete any original files! Now that you have, you'll probably have to reinstall the game to make it work again.
Furthermore, BSP swapping is a bit of trial and error. You have to try and find the "compatible" BSPs. With some, alas, the game will simply crash. If so, revert your changes and try again.