The current software
The current software in use is the "Lightburn" software. It is made for laser cutting, but can be modified to work with CNC milling.
image
Possible improvements
Replace with a different CNC software, more suited for our needs
To do this we would need to research what other softwares could meet our needs, and take the time to learn it. Spending the time getting very proficient with Lightburn might be more effective.
Create our own software with image overlay and G-code generation
Both of these technologies exist. So there is probably some possibility to buy something of-the-shelves as writing the code for this software would probably take a lot of time.