Usually we use a phone to upgrade the nrf52840 devices. can i upgrade the device by two sets of nrf52840?

[yubhua]

I have two nrf52840 devices and conneted them each other.  one is slave mode and other is master mode. can i upgrade the slave device by the master?

[HPD]

What do you mean by Upgrade ? Do you want to change the slave device to master or anything else ?