Multichannel Renders from Batch and chopping shots together

Anybody have a hot tip on how to join 2 different clips rendered as Mulitchannel clips from Batch, gesturally, or in the timeline, where the resulting clip continues to be multichannel?

Sorry about the delay. Must have lost this in the shuffle. Just turn off all tlfx that involve a matte, such as action with “use Back” turned on, or comp, and contain. Once contained it should show all the behaviors of a regular multichannel clip.