tar czf bpi-m3-latest-fixes.tgz /usr/lib/u-boot/bananapi/bpi-m3
then put bpi-m3-latest-fixes.tgz online (github!) and write instructions for users how to get the fixes with the other OS images you provide? Basically it’s just
cd / && wget -O - https://github.com/BPI-SINOVOIP/BPI-M3-bsp/blob/master/bpi-m3-latest-fixes.tgz | tar xzf -
(and this should include “bpi-bootsel” itself which should learn this capability)