There is an option "Who Paid for the Bill?" The selection option is The Business. How do you add other options like the Owner?

To any anyone like owner to the drop down list you need to add them as an employee. So the system can track them. 
If you’re setting up employees it’s best you use the P2C file you find in your ROS account. Manually creating employees will lead to mistakes. The P2C file will instantly configure everything in Bullet. 

Pete