ExDancer
How do you plug it into the TV Chestnut, is it a special hearing aid? Mine are NHS but I wasn't given any instructions on connecting them to the TV. My husband could do with one, the sound from his football hurts my ears when he has the volume turned up to his preferred level.
Naturally he won't admit he's even a teeny weeny bit deaf!
Mine are Phonak Audeo from Boots so they are not NHS. They gave me a free Phonak TV Connector which I just plugged into the headphone socket and it connected wirelessly to my ears! Maybe ask if there is a TV Connector for your model? Obviously you'd have to buy it.
I assume that one person can connect directly to the headphone socket, or two people if you use an adaptor to create two sockets. You would have to share the same sound level on the TV and there would be no sound in the room, so a third person with no hearing aid would hear nothing.