Observation checklists: alert limitations

Summary:

Ability to switch off or customise standard email alert for observation checklist functionality

Content (required):

We have just started using observation checklists in Learning. When we assign this to a colleague the manager is notified to complete the checklist on the colleague's progress in role. The standard alert that this triggers does not seem to be amendable nor can we see a way to switch it off so we can replace with a custom alert. This isn't a great experience for a manager as we want to put some guidance in the email that goes to them. Are there any ideas of how to do this?