Hello,
You will need to provide more information as to what you are trying to accomplish, I´m not sure if what you are asking is to add multiple businesses?
For the sync issues you will need to provide more information as well, what type of issue are you having?
You might also want to contact NCH Technical Support for this, you can create a support ticket from the link below:
- https://www.nch.com.au/support/index.html 
Good luck!