I appreciate the follow-up question, Alex. Let me step in and provide additional information about the limitations of importing files into QuickBooks Online (QBO).

Yes. Currently, we're unable to import estimate transactions using IIF and CSV files to all QBO plans, including Advanced. It's only available in QuickBooks Desktop (QBDT). However, we can consider my colleague's suggestion above about manually entering them or visiting the QuickBooks App Center to look for a third-party app we can use. 

Here's a collection of frequently asked questions about importing files: Common questions about importing data to QuickBooks Online. It contains the list of transactions you can import and more relevant information about transferring data to QBO.

Moreover, you may create a personalized look for your estimates and other sales forms. This way, you can include information relevant to your business and decide what details your customers can view.

Feel free to visit the Community if you have additional questions about managing estimates. We're here to make sure your concerns are well-taken care of. Have a nice day.