Ten “active” files is the important distinction. In the future archive files instead of deleting them.
Also you can produce and save a DXF to store for later.
But
Now you have to convert a NC file to a DXF file.
NC to DXF plotter is another search term for this.
this one worked for me
http://www.ncplot.com/ncplotv2/download.htm
it can have glitches depend on how it interperates the z axis movements.
glitches Example
You can project these all back to the same plane