For the full access JBD xiaoxiang based apps on Android (including Carplounge on Google Play), go to App Setting and enter a unique name in the Device Model field for each BMS. It's easier that way to choose which one you want to connect to.
For multiple simultaneously BT polling, LiontronMulti on Google Play averages voltage and sums remaining amp hours of multiple JBD BMS. It is view only but still useful. I added three batteries to it and once added, it connects automatically to all of your JBD BMS batteries that are in range just by opening the app.