I could not found satisfied answer. I believe you have simillar issue with fonts in dxf files since curves after export to DXF are not the single splain curvature but consists of multi lines. It is a problem for laser cutting process.
Im using draftsight for dxf edition. What I've tried to do since now is create one block or one group for each digit but this solution is not correct for laser input.
An example is attached. Thank you for your support.