You can't, @bk_eli. Let me provide the reason why.
It's important to note that QuickBooks Desktop (QBDT) and QuickBooks Online (QBO) are distinct platforms that operate independently of each other. This means that data entered or modified in one platform will not automatically sync with the other platform.
On the other hand, if you need to combine data from both platforms, you can consider using third-party applications.
Additionally, you can refer to these articles for a guide about moving your data from QBDT to QBO and vice versa:
Let us know if you have other questions about QuickBooks. We'll be here to help you in any way we can. Take care!