I see. It is certainly not a matter of adding a single paragraph to an existing code, but rather, as Martin indicated, you have to start from scratch.
But to give you a start:
*have you found the CODM user guide?
https://www.hauptwerk.com/clientuploads ... rGuide.pdf*Then, have you been able to follow the steps on page 4?
If so, then the next steps are
*Can you locate, amongst others, the rank and the stop tables? Can you make guesses which entry in the tables belongs to which items?
*Try to remove one stop from the stop table of the copied&renamed&edited .CustomOrgan_Hauptwerk_xml file (don't edit the original) . You need to remove the entire entry for that specific stop, including all its attributes. Are you able to load the custom organ again? And do you see the stop removed from the screen?
*Try to add a Kromhoorn stop to the stop table: copy an entire existing stop table entry, rename to "Kromhoorn", label it as "Kromhoorn 8", specify new screen coordinates and reload the custom organ. Does the Kromhoorn stop appear on the expected position?
*The Kromhoorn stop will be mute. You need to add an entry in the rank table to load the sound files from the Rotterdam sample set folders, and you need a stoprank entry to connect the rank (sound files) to the stop.
I guess it will be weekend before you arrive at the last step, which actually demands a bit more explanation. And probably you will get confused earlier, but you appear to be quite committed