r/bluetoothspeaker

My car has a built-in DVD player, but being 20 years old does not have a built-in Bluetooth receiver. I have used an adapter to connect my phone to the speakers before, and I just got to wondering if I could use one to play movies on the DVD player with my phone. I don't have the adapter anymore, so I can't go out and test it out for myself, so I googled it, couldn't find a straight answer, but ended up here, and thought there was no harm in asking.

My wife is trying to use a BT speaker for her aquafit class. She plays music from her phone and wants to also have the speaker play the verbal instructions that she provides via a headset with an aux plug. (So she can speak over the music, etc.). Most speakers have cutoffs so if you plug something into the aux jack the speaker takes signal only from that input source. Are there any you can suggest that allow "both at one time" playback? Or, any workarounds? TIA