Answer
There is a web synchronisation feature available in Lightning Payroll that can be used to sync your data between your Lightning Payroll installations and with the web application. (Before setting this feature up, we strongly recommend ensuring all devices are up-to-date with the same data by using our Online Backups feature, or Create/Restore Backup through the Tools menu.) To turn web synchronisation on, go to Settings >> Other Settings. In here you will see 3 options:
After ticking any one of these options, you will be asked to log in to enable the feature. The details required here are the same login details that you would use when logging into our website via the Client Login. Please note that this is separate to your application password, your subscription ID, or your Online Backups password. If you are having trouble with your password on this screen, please use the Forgotten Password? option displayed below the fields.
After logging in, you will be emailed a 6-digit two-factor authentication (2FA) code to enter into the next screen. If your account is secured with Google Authenticator, please use the 2FA code generated by the app instead.
After entering the 2FA code, the web sync feature will now be active.
Sync Data Up To Web App?:
This option, when enabled, will detect when changes are made inside Lightning Payroll and upload them to the web application.
Sync Data Down To Desktop App?:
This option will detect when more recent changes are made online and will download and restore them into your Lightning Payroll desktop application.
With these first 2 options, checks are done automatically every 5 minutes, and a refresh button will be displayed at the bottom right of the program. This button can be used for manual checking if you want to check in between the 5 minute interval.
Manually control web sync uploads/downloads?:
This option will not automatically synchronise your information, giving you control over when backups are created and/or restored. Instead of the refresh button mentioned with the previous 2 options, a download and upload button is displayed down the bottom-right instead.
These diagrams below demonstrate how the feature works between the web application and 1 installation, and how it works between the web application and 2 installations:

