Hey,
Yeah i've been doing this - i just make alternate courts for my Suns and have them in another folder ready for playoff time  - Im a total noob to editing but worked it out - i do have photoshop skills to understand how to edit though.
might help to watch this -
https://www.youtube.com/watch?v=iqIFHgL9U8cHavent done it for a while but you basically have to export the court file using the mod tool - Find the court you want to edit within your season / roster by opening your roster in RedMC and find the court file that is aligned with your team. Then open that file in the 2k Modtool - Find the Court layer within that file (there is drop down that lets you view different layers of the file)  - export the court art layer as a DDS file. Then you can open that court DDS layer file in GIMP  and add any additional court art work (must be a transparent art file - best use png file ) - Use free editing software Gimp . Save the DDS file (couple of settings youve got to tick - should be in that video) and then update the  edited layer back in the mod tool - best to save the court as a diff name so you don't overwrite the original - then when you're ready to use the court - copy your edited court and over right the file in the  main file structure.
 
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