If you are already using multiboot then it won't make any difference to you and you don't need to update anything, just flash 5.4 to any slot you want (except recovery).
The automated process is only for initial setup, so the only time you would see it is if you replaced the recovery image, which would mean you loose the currently installed images in slots 1,2,3
The automated process is only for initial setup, so the only time you would see it is if you replaced the recovery image, which would mean you loose the currently installed images in slots 1,2,3