Damn right, she has been recently banned from one of the servers she mainly spoke in after the owner got tired of tolerating and telling her to stop pinging people for no reason, DMing them and harassing them. Now that she has no server to talk, she pretty much just lurks around several random Discord servers. It's only a matter of time before she steps into another groomer server like The Arkadian that will take advantage of her autism and hence starting another drama. (btw she's still contacting them)
Even if you guys tried to make a server she could chill in, I could assure that people would likely run out of patience trying to ask her to stop pinging and DMing at random, which is pretty distracting and annoying. I get it, it's autism but still. That's the main reason why she gets kicked off many servers. You can see that by yourself by joining any server she sends you an invite to.
The only people who can really stop her from using Discord are her parents. But I doubt they would do much. You could try talking to her sister about this.