If you want to go from new to old, you can export the BAQ, change the extension to .zip, you can see a text file that has the version number. It starts with a 3. You can change that on the newer one then change the extension back to .BAQ. It will then let you bring it into the older system.
Whether or not it works is dependant on a bunch of factors, but if it’s relatively simple it seems to work a majority of the time.