Generic mask images for multi-camera setups

[3create]

Hi,

I'm using a rig with 6 cameras. The images are imported to MS with the multi-camera workflow (master/slaves).
Works like a charm, however, some of the images have parts of the rig in them (can't be avoided in this specific setup).

In a conventional MS-workflow it would be very easy to select a single mask image for each camera group (i.e. "Cam5_xxxx.tif" -> "Cam5_mask.png" / "Cam6_xxxx.tif" -> "Cam6_mask.png").
However, if I select a single mask image for the master, it applies it to all slave groups.
What's the solution to this, are there any "{}"-placeholders which would work when choosing the mask-images?

A workaround which did do the job, was to create hundreds of "Cam5_xxxx_mask.png" images and use "{filename}_mask.png as a template.
But that is highly inefficient, as Cam5_mask.png is always the same image...

Thanks in advance!