On Hold light on all phones in a group

I have Polycom 501 phones each with a different extension. I can make them all ring. Once someone picks up all others drop off.

The problem is when caller wants to talk to a different person.

Is there a way to put caller on hold so someone can pick up at a different phone? Parking call is a pain for small environments.

E.g. Secretary gets call. Caller asks for boss. She puts caller on hold and boss picks up on flashing line.

I guess it’s like a blind transfer to all extensions without the ringing. But we dont want autoattendant to pick up, just keep ringing until call is answered.

Any ideas how this could be achieved with Asterisk?