Actually, this version accept only one Master target if you're using Standard BSC schema with sub address.
But you can use other kind of message without sub address. Open the actions.xml file, you will find messages for X10 connector. Thoses messages have a fixed target (ersp.X10 connector.XXXXX.*) and the xlobby variable (the subaddress) is given to the ID field like ID=*Xlobby*
Then when you use X10 connector : On in your xlobby event, fill the variable with A1 for exemple, and the plug will replace *Xlobby* with A1 so you will have a message with target = ERSP.X10 connector.XXXX.* and in the first block a line with ID=A1.
The next version will let you give a Master variable (for the master target part) for each device...wait and see [/b]