Hi Fabio!
Yes, I agree. It is a little bit to dynamic However, to keep the ID do the following. Right click on the camera image. At the top of the menu you can enable/disable the camera. Disable it. It will keep the position/ID, but it will not show up in the clients so the ID for the rest of the cameras are preserved.
-Henrik
Hm, I am not sure where you find that SourceUID ? Usually that long text string, Token, is a combination of several parameters like camera source, access control, … or camera source, video, date, time, … access. It sure is an internal format.
Here you can find more about WebAPI for control of NCS. It is better to use these standard commands Netcam Studio - Network Camera Surveillance Software
-Henrik