From
this thread it seems you can add the SD card in FS-UAE, and copy stuff directly to the amiga partitions.
It is also possible to have both amiga and FAT partitions on the same card.
I haven't done it myself, but I've read the MBR needs to be positioned at the very beginning of the drive.
Mac OS disk utility can do this part. Leave at least some space for the RDB before the FAT partition.
Then setup the amiga partitions without overlapping the FAT one
As I said I never tried it, but IIRC HDInstTools should recognize the MBR and FAT partitions and let you position the amiga partitions easily.
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