Assign values to dropdown menu selections

If the user selects "Open" in A9, I want the cells that would have been populated if a different choice was selected in the dropdown menu to be editable to whatever the user would like them to be.

Think of all other selections in the dropdown menu as guidlines or pre-set values, but the "Open" selection allows them to create their own guidlines.

Also, I'm working on a mock-up. Should be done shortly.

Here is a reference doc.

I have put the formula in cell B10, but it will eventually be populated down and over so all of the cells are populated.

When "Open" is selected, I want to be able to add in my own value in cell B10. However, when I select a different option in the dropdown menu, I want it to reference back to the cell from the formula.

Hope this helps.