Adding a local channel to an existing simple_bridge using AMI and the dial plan

I am working on a script to play an audio file to all channels inside a specific existing simple_bridge using AMI. I am able to create a local channel and also have the bridgeId. Looking for more information on how to add the local channel to the simple_bridge via the dial plan. And execute an audio playback.

What direction do I need to go to make this work.

ip-172-26-12-228*CLI> bridge show all
Bridge-ID                            Chans Type            Technology      Duration
c8a19539-9727-4d5d-bdcb-4ebf39f1c5c1     2 basic           simple_bridge   04:00:20
<--- Examining AMI action: -->
Action: Login
Username: mark
Secret: <redacted from logging>
Events: off

  == Manager 'mark' logged on from
<--- Examining AMI action: -->
Action: Originate
Channel: LOCAL/play_sound@my_context
Async: true
Variable: BRIDGEID=c8a19539-9727-4d5d-bdcb-4ebf39f1c5c1
Variable: SOUND=/etc/asterisk/dialplans/soundfiles/demo

    -- Called play_sound@my_context
    -- Executing [play_sound@my_context:1] NoOp("Local/play_sound@my_context-00000050;2", "") in new stack
    -- Executing [play_sound@my_context:2] Answer("Local/play_sound@my_context-00000050;2", "") in new stack
    -- Local/play_sound@my_context-00000050;1 answered
    -- Executing [play_sound@my_context:1] NoOp("Local/play_sound@my_context-00000050;1", "") in new stack
    -- Executing [play_sound@my_context:2] Answer("Local/play_sound@my_context-00000050;1", "") in new stack
    -- Executing [play_sound@my_context:3] Verbose("Local/play_sound@my_context-00000050;1", "Local channelId 1714412926.291") in new stack
Local channelId 1714412926.291
    -- Executing [play_sound@my_context:4] Verbose("Local/play_sound@my_context-00000050;1", "Existing bridgeId c8a19539-9727-4d5d-bdcb-4ebf39f1c5c1") in new stack
Existing bridgeId c8a19539-9727-4d5d-bdcb-4ebf39f1c5c1
    -- Executing [play_sound@my_context:5] Verbose("Local/play_sound@my_context-00000050;1", "Soundfile /etc/asterisk/dialplans/soundfiles/demo") in new stack
Soundfile /etc/asterisk/dialplans/soundfiles/demo
    -- Auto fallthrough, channel 'Local/play_sound@my_context-00000050;1' status is 'UNKNOWN'
  == Spawn extension (my_context, play_sound, 2) exited non-zero on 'Local/play_sound@my_context-00000050;2'
<--- Examining AMI action: -->
Action: Logoff

  == Manager 'mark' logged off from


exten => play_sound,1,NoOp()
same => n,Answer()
same => n,Verbose(Local channelId ${CDR(uniqueid)})
same => n,Verbose(Existing bridgeId ${BRIDGEID})
same => n,Verbose(Soundfile ${SOUND})
; same => n,BridgeAdd(${BRIDGEID})
; same => n,Playback(${SOUND}) ; Play the specified sound file
; same => n,Hangup()