Hi K,

Yes, you can create a main task/sub task drop down box in Excel using a feature called "Grouping". Here's how you can do it:

1. First, create a list of all your tasks in Excel, with the main tasks in one column and the sub tasks in another column.
2. Select the range of cells that contains your tasks.
3. Go to the "Data" tab in the ribbon and click on "Group".
4. In the "Group" dialog box, select "Rows" and "Auto Outline".
5. Click "OK" to group your tasks.
6. You should now see a little cross next to each main task. Click on the cross to expand or collapse the sub tasks.
7. You can also use the "+" and "-" symbols in the left margin to expand or collapse the groups.

That's it! You now have a main task/sub task drop down box in Excel. You can also customize the appearance of the grouping by going to the "Data" tab and selecting "Grouping Options".