I have to pop uut for an hour but yes, I will try this as soon as I get back!
To be sure, I first flash FS in the same way as the MAIN, add it to the "files" field and hit "flash". Then the custom pack in the MISC files field using the "..." button and then hitting "flash"
I can't tell you how glad I am for your time and effort. Hope I can repay in some way!
Best regards!