@Evan_Reminick You would just need to add those accounts to Insync again, making sure during setup to select the previous syncing folder for each. If you had selective sync settings previously set, it would be best to set that up again at this point as well.
Insync will then proceed to process and match your existing files in the old syncing folders to your existing files on Drive. This will work best if there are no discrepancies between your local files and your files on Drive. Let us know if any issues come up!