switch between root'spartition

hy,

i know it's off topic but i don't know where i can put my quesiton.

so i have a Bananapi m2 with bananian =>> there are two partition : boot ( mmcblk0p1) and root(mmcblk1)

Can i add another root's parition(mmcblk2) and switch between the two root's partition?

'V£
^‰UÐ?,  L        _E#Ö                                   D    #--------------------------------------------------------------------------------------------------------------------------------
# Boot loader script to boot with different boot methods for old and new kernel
# Credits: https://github.com/igorpecovnik - Thank you for this great script!
#--------------------------------------------------------------------------------------------------------------------------------
if load mmc 0:1 0x00000000 uImage-next
then
# mainline kernel >= 4.x
#--------------------------------------------------------------------------------------------------------------------------------
setenv bootargs console=ttyS0,115200 console=tty0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
load mmc 0:1 0x49000000 dtb/${fdtfile}
load mmc 0:1 0x46000000 uImage-next
bootm 0x46000000 - 0x49000000
#--------------------------------------------------------------------------------------------------------------------------------
else
# sunxi 3.4.x
#--------------------------------------------------------------------------------------------------------------------------------
setenv bootargs console=ttyS0,115200 console=tty0 console=tty1 sunxi_g2d_mem_reserve=0 sunxi_ve_mem_reserve=0 hdmi.audio=EDID:0 disp.screen0_output_mode=EDID:1680x1050p60 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
setenv bootm_boot_mode sec
load mmc 0:1 0x43000000 script.bin
load mmc 0:1 0x48000000 uImage
bootm 0x48000000
#--------------------------------------------------------------------------------------------------------------------------------
fi

This is the boot.scr

I have tried to remplace root=/dev/mmcblk0p2 by root=/dev/mmcblk0p3 but it didn't  work.

Can you help me please ?