Hi Mallus,
OtherImage is a catch-all for images stored in other IFD's of TIFF-type files, so its location isn't fixed. Even within NEF files, OtherImage may be located in SubIFD2 (as in D800 files), or SubIFD1 (as added by Nikon Capture). It would be difficult to make this writable, but I'll see what I can do.
- Phil