Creating an audience containing Batch and Edge

I have successfully created the following audiences separately:

1. Edge segmentation, using Edge merge policy [A]
2. Batch segmentation, using default batch merge policy [B]

Adobe Support has advised me to create an audience combining the two using an OR condition, in order to identify and capture returning visitors over a longer period of time. 

The goal is for individuals to flow into Target and be served personalized experiences, beyond the 24 hour limit within Edge profile qualification.

In the segment builder, I have set Attributes as: [A] OR [B]

I have tried the following combinations of Evaluation Method and Merge Policy, but regardless of the combination I receive the same error outcome with the following message:

When trying to save, I receive this error:

One or more of your referenced audiences uses a merge policy different from the one selected for this audience. Verify merge policies of referenced audiences. If you feel you are seeing this message in error, try saving this audience again.

I suspect it is because one audience is Edge and one audience is Batch, and each requires its specific merge policy.

What would be the proper approach to creating an audience which combines Edge and Batch?