hi,chansookang
Thank you for contacting us.
I know what you mean. I think you can operate the payload in software. LLCEAF cannot recognize the messages inside LLCE. If you want to do so, you can purchase FDK and modify the LLCE code.
In addition, refer to the LLCE_firmware_user_guide, no payload manipulation is implemented (e.g. payload split).

BR
Joey