DXF default layer mapping

Hi guys,

I'm trying to do a seemingly simple task, but without success. I'm exporting DXF files for laser cutting and engraving. We have an automatic script for assembly export (part by part) but all the cutting layers go to layer "0" and I would like to change that to "3". The models are already set up so that cosmetic sketchets are mapped to specific drawing layers, everything else is unassigned (therefore go to layer "0").

I was experimenting with map_layer commands in dxf_export.pro file, and I was able to map any existing layers but not the default "0" layer. Is there a way to do that?

Thanks a lot