BurnFit officially does not support data sharing with other accounts in real-time.
However, it is possible to move current data to another account in an unofficial way.
How to move current data to another account
Step 1
Log in to the account with the data you want to save and retrieve the data from the cloud through My Page 'Backup My Records'
Step2
Go to My Page → Options → Click on Account and 'Logout'
Step3
Log in to the new account to which you want to move the data
Step4
In the 'Backup My Records' screen that automatically runs, upload local data to the logged-in account via 'Export'.
Caution! If there is data in the account you are moving to, it will be overwritten with new data.