Multiple instances of Forge/Fabric Can be run at the same time using Essential Installer! Here's how
You'll need Windows, the Minecraft Launcher (https://www.minecraft.net/en-us/store/minecraft-deluxe-collection-pc), and the file at https://ufile.io/56teitql . Credit to @Sk1er!
Start the Minecraft Launcher and initialize Minecraft at least once.
Close the Minecraft Launcher.
Then, start the attached file.