Hacking Save restore Problem with Retro Game Challenge

[Gabelvampir]

Hey,

I need help. I just bought Retro Game Challenge and wanted to transfer my Supercard MiniSD savegame onto the Cartridge via Rudolph's
NDS Backup Tool Slot 2. The tool works, I saved and restored some saves in the past and it also works with Retro Game Challenge
in principle. But the problem is that the Supercard MiniSD save is 256k big, while the original Game Card save is just 64k in size.
I already tried some conversions with the web save converter from ShunyWeb (for example convert to RAW 64k force), but no luck.

Does somebody have any idea what to do to make my save work on the Cartridge?

Thanks in advance.