This is more of a question because I don't use ASUS Merlin at the moment, but I may do so if it allows to keep custom IPTables and EBTables via CLI after router reprovisions. Stock ASUS firmware erases all additional/custom IPTables rules added by CLI whenever user makes changes in ASUS router GUI. I guess writing some cron scripts can do the job, but that's not a good solution. I want my IPTables to stick even settings are changed afterwards within ASUS router GUI.