Is it possible to change the Bluetooth Address (BT_ADDR) configured on the BT850, BT860 modules or the BT851 dongle?

Yes, it is possible to write a custom Bluetooth address during run time by sending the HCI command, Write_BD_ADDR. You can also use the AIROC Bluetooth Test and Debug tool to select Write_BD_ADDR for setting a custom address.

Note: The Write_BD_ADDR command writes the Bluetooth Address to the chipset's internal RAM, which disappears after a power cycle.