Hi there! Merging multiple single worksheet Excel files into one file while maintaining each worksheet into its own tab is a common task in Excel. Here's how you can do it step by step:

1. Open a new Excel workbook where you want to merge all the single sheeted workbooks.
2. Click on the "Insert" tab and select "Worksheet" to add a new worksheet.
3. Rename the new worksheet to something like "Merged Sheets".
4. Open the first single sheeted workbook that you want to merge.
5. Right-click on the worksheet tab and select "Move or Copy".
6. In the "Move or Copy" dialog box, select the "Merged Sheets" workbook from the "To book" drop-down list.
7. Check the "Create a copy" checkbox and click "OK".
8. Repeat steps 4-7 for all the single sheeted workbooks that you want to merge.
9. Once you have copied all the worksheets to the "Merged Sheets" workbook, you can rearrange them in any order you want by dragging and dropping the worksheet tabs.
10. Save the "Merged Sheets" workbook with a new name.

That's it! You have successfully merged multiple single worksheet Excel files into one file while maintaining each worksheet into its own tab.