Asterisk: how to stop conference1 to listen from conference2 when user is connected to both

Our requirements:

• The user only sends audio to conference1, that is, it does not send audio to conference2.
• The user only receives audio from conference2, i.e. does not receive audio from conference 1.
• Conference1 should not hear conference2 audio

Failed Attempt 1
 - We put the user in his conference room (say userConf).
 - We created local channels with userConf at conference1 and at conference2.
 - Using manageraction_muteAudio, we have implemented the first two constraints.
This attempt failed because userConf moved the audio from conference2 to conference1.

Unable to attempt 2
 - We are putting user in conference2 muted.
 - We used chanspy to listen to the user.
This attempt failed because we didn't know how to take the chanspy leg to the conference1.

Any suggestion for the aforementioned two unsuccessful attempts or a new way to solve this problem would be much appreciated.