you need to convert the sound with "ealayer3" to .snr format and replace the "CustomMusic_BossBattleExtended.snr" file, then you can change the sound item name in the "CustomMusic_BossBattleExtended.prop.xml" prop file.
When you understand how it works you can change the names of the prop.xml files, but to start you can go testing
sorry for the google translate
