Which is why the zombies will harm only the players with the script & you must be host to start zombies online mp for abusive reasons of course. Motorsport71 told me that he had already tested it with a few people and worked but the project was on ice because he couldn't compile his work, so I helped complie & test. There are two version, first one is the original zombies and the other has special abilities zombies.
Just because you don't know, doesn't make it not possible...