It would be my pleasure to help you explore all available options for making QuickBooks Online (QBO) work like your business needs. Do you mind explaining a bit more about how you would like this FOB to work? Having this information will enable me to make the best possible suggestion for your situation.
In the meantime, QBO does offer the support of thousands of various third-party applications for any functionality you may need. To see if there's an app that can help you accomplish this, head to the Intuit App Center and type a keyword like "FOB" in the search bar.
Please keep me posted here on how I can help you succeed with QuickBooks. Thanks for reaching out. I'll be standing by for your reply.