single bluetooth device to many other device

Yes of course, if you turn on your bluetooth enabled mobile phone, it can detect and connect few other devices.

In a Bluetooth piconet one master can communicate up to 7 active slaves, there can be some other up to 248 devices which are in sleep mode (may participate to communication actively when another active device goes into sleep mode).

In Bluetooth scatternets (interconnected piconets) number of devices are not limited. Some slaves used as a bridge by participating two or more piconets. One of the most advanced topology defined for Bluetooth scatternets is Cube Connected Cycles architecture.