Changing voice to Videogames NPCs

Hello to the community.
I don’t know is this is the right forum to ask, I’ new to this. So please be patient and if this is the case, move this thread to the right place.
My problem is simple. I’d like to create a mod for Skyrim, probably the nicest RPG of the history of videogames, in which I’m going to change the voice of a lot of NPC characters.

This is why Bethesda, the creator of the game, went really bad in selecting the voice actors, and it turns out that they recorded 31 NPCs with the same voice, without worring to use - at least - some kind of filtering or voice modification.

I’d like to create a mod which uses 31 kind (or something) of filters - also lightly different from each other - and process the files.
I know that there are some voice-modification programs, but they are mainly devoted to work in real time taking the voice from a mic into programs like skype or similars. These programs are hardly to test and many - those I have seen at least - have no recorded file editing features.

So I’m wandering if is there any kind of “plug-in” for Audacity that can help me to do so ? A “voice modifier plug-in” ?
Also is there any way to register a kind of “filter profile” in the parameters of Audacity to make a mind of preset to be recalled quickly ?
I’m asking because it should be required to recall a “preset” because a file (or several) has been forgotten or has been newly discovered into a scene that was previously hidden or something…

Thanks in advance for any help you may provide.