Multiple Bluetooth audio devices attached to Columbus...?

I've got a Columbus fitted and also Bluetooth module (7P6035730C) and I'm just wondering if it's possible to attach multiple phones at the same time? Even if only to stream music from different phones....wouldn't need to have full phone function.

The reason I ask is that sometimes when I fire the car up, if I was streaming music via Bluetooth when I last used it, then it comes up with "Select Bluetooth audio device:" and shows a list with one item in it (i.e. my phone) with "Device 1" next to it...which kind of implies that it would be possible to add more devices. But I can't find any way of doing so!

Any ideas...?