Helped, thank you very much!

Okay so, let's say you will want to get Marge's animation on homer1
To achieve that, you go in scripts\missions\level01\leveli.mfk
You must go to the line that has

AddCharacter("homer", "homer");

You will want to replace homer with marge. and will now be playing as both marge with her animation.
If you want to use your animation for characters OTHER than marge, then you will want to go to art\chars
From there, you will copy marge's animation (marge.cho) and rename it to any other character skeleton, for example we'll take ned.
Copy marge.cho and rename it to ned.cho first. Open ned.cho with any text editor (I suggest notepad++, it is free and very useful.) and simply replace the word marge with ned. Don't replace 'mrg' though, because that's part of an animation name and you really shouldn't touch them for this one easy thing.
When you're done with ned.cho, you will want to make a copy of marge_a.p3d and rename it to ned_a.p3d.and you're good to go.You will now have this animation called ned and you can now simply go scripts\missions\level01\leveli.mfk and simply edit the code and make it look like

AddCharacter("ned", "ned");

Remember, this works with ALL of the game characters and ned was just an example. If you want to achieve homer with marge's animation, simply copy marge.cho, rename it to homer.cho and replace marge with homer everywhere inside it, then copy marge_a.p3d and rename it homer_a.p3d
I hope this satisfies you

thank you, I don't edit the simpsons files much

I have a problem with the mod launcher, which when I open it, seconds later the game closes and says: "Lucas Simpsons Hit & Run Launcher.exe will be compressed only after closing the application using it. Modifications will be lost if you close WinRAR before that

Extract the launcher to your desktop and run it

ok thanks guys

Such a functionality uses an external injectable (hack) by the Mod Launcher to function in the game. Afaik its in the game, just disabled in code.

You can't do this unless you dissemble the actual executable and create a patch, or create your own injectable to allow this function to operate. its nothing that could be done by modifying any of the other games files. Using the Mod Launcher is much much easier and gives you access to other cool stuff too. You don't have to run mods with it.

I have a problem with the mod launcher, which when I open it, seconds later the game closes and says: "Lucas Simpsons Hit & Run Launcher.exe will be compressed only after closing the application using it. Modifications will be lost if you close WinRAR before that "

but I play mods without the mod launcher