How to run multiple command line processes simultaneously in the background

I'm trying to run multiple system processes in the background.

Currently First the one process runs, and then the next. I'm trying to get them to run at the same time. When I do it manually from Terminal, I can ru multiple versions simultaneously.

This is a part of the script I'm using.

I'm looking to have the Dropbox section execute at the same time as the Google Drive section, as a separate process (running simultaneously).

sf.ui.finder.appActivate();

const rclone = '/usr/local/bin/rclone';
const rcloneDropbox = "Dropbox:Nazzy-Uploads-Dropbox";
const rcloneGoogleDrive = "Google Drive:NAZZY-Uploads-Drive";

var selectedFolder = sf.ui.finder.firstSelectedPath;
var folderName = selectedFolder.match(/([^\/]*)\/*$/)[1];
var rcloneFolderDropbox = rcloneDropbox + '/' + folderName;
var rcloneFolderGoogleDrive = rcloneGoogleDrive + '/' + folderName;

    // Copy to rclone: Dropbox
    sf.engine.runInBackground(() => {

        sf.system.exec({
            commandLine: `
            "${rclone}" copy "${selectedFolder}" "${rcloneFolderDropbox}" --create-empty-src-dirs
            `,
            executionMode: 'Background',
        });

    });

    // Copy to rclone: Google Drive
    sf.engine.runInBackground(() => {

        sf.system.exec({
            commandLine: `
            "${rclone}" copy "${selectedFolder}" "${rcloneFolderGoogleDrive}" --create-empty-src-dirs
            `,
            executionMode: 'Background',
        });

    });