Can I add a line on an estime? example if I have 40 lines on an estimate and I want to add a line in between line 19 and 20, is it possible without starting over?

Hello jack-renobrio-co,

Welcome to Community!  QuickBooks Online makes it easy to create and send estimates to your customers, so they can approve your work.  I can see how you would benefit from being able to add additional lines as needed, to save valuable time.  Although you can add additional lines at the bottom of the items list, there currently isn't a way to add them between the existing lines.  

If you would like to see this option in future updates, please feel free to submit a suggestion to our Development team, by going to your Settings ⚙, then select Feedback. Enter your product suggestions, then hit Next to submit.  In the interim, you may need to copy/past the line items, to keep your list organized.

Feel free to reach out again, if you have other questions.  We would be happy to help!