Sophos SUM password lost to add

Hello all. So we have 45 UTM 9.x devices managed via a SUM server running on a cloud hosted Linux box. All is well. However we do not remember the password to add a new UTM to the SUM server. We have the password to login to the sum interface. However we do not have the one where I can add a device to SUM via the UTM interface

Is there a way to recover this password? If not then how do I reset it? And, more importantly, what happens to all the 45 UTM devices that are currently managed.? Do I need to update each one of them?

Thanks for any info.

Dave