Can one Master unit communicate to many Slave units

BT232

BT232 can be only one to one (master to slave). Because each BT232 unit means only a virtual COM port, no matter set as Master or Slave.

The way to be one to many will be, theoratically, bluetooth dongle on PC to many bluetooth devices.

Theoratically, the bluetooth dongle on PC can be paired to each different bluetooth devices by creating each different virtual COM port on PC. But this is a theoratical rule, and depends on different brands made bluetooth dongles.