Circular Reference with drop-down list - excel

Question

Is it possible in MS. Excel or VBA to have a circular reference with a drop-down list?
Here is what I am after: I want to generate on two sheets (sheet 1, sheet 2) a drop down list that says either "Complete" or "Incomplete." If I change sheet 1 from Complete to Incomplete, I want sheet 2 to say the same thing, but I also want vice versa
(If I change sheet 2 from Complete to Incomplete, I want sheet 1 to change).
Is this possible?

Answer 1

Acting on a change in any of the worksheets' B5 range seems a likely way to proceed but the individual Worksheet_Change event macros have some limitations.
The code has to be repeated across many worksheet code sheets and any modifications have to be cloned across the same. New worksheets require the sub procedure to be incorporated into their own code sheets.
Without disabling events before writing new values, each worksheet receiving a new value is going to initiate its own Worksheet_Change event macro which in turn will rewrite values which will trigger more events. A cascade event failure is almost sure to happen.
By exchanging the Worksheet_Change event macro for the more universal Workbook_SheetChange event macro located in the ThisWorkbook code sheet, all of the code can be localized to a single location. Adjustments are made in a single place and new worksheet will automatically be added to the queue of worksheets to process. They can easily be added to the array of worksheet not to process as well.
Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
If Target.Address = "$B$5" And Sh.Name <> "Sheet3" Then
On Error GoTo bm_Safe_Exit
Application.EnableEvents = False
Dim w As Long
For w = 1 To Worksheets.Count
With Worksheets(w)
'skip this worksheet and Sheet3
If CBool(UBound(Filter(Array(Sh.Name, "Sheet3"), _
.Name, False, vbTextCompare))) Then
.Range("B5") = Target.Value
'.Range("B5").Interior.ColorIndex = 3 '<~~testing purposes
End If
End With
Next w
End If
bm_Safe_Exit:
Application.EnableEvents = True
End Sub
Any worksheet that is not to receive an update to the value in its own B5 cell can be added to the array used in the Filter function. Currently, Sheet3 and the worksheet that initiated the Workbook_SheetChange event are excluded.

Answer 2

I would create a hidden sheet that contains the range for input and the linked cell. Then link both drop downs to the list and the linked cell. Then when you change one it will change the other. The key here is the Linked Cell. This is assuming Excel 2013, using the Form control Combo Box.

Answer 3

Please have a look at #Jeeped's answer as it is the most efficient answer.
After a little trial and error I've gotten this to work with a cell with a "Data Validation" dropdown menu. In my test case, I had 3 sheets with a Data Validation list in cell $B$5 on each worksheet linked to a list on a hidden sheet to populate the list, the sheet with the options list was "Sheet3" and did not contain a data validation list.
The Code below needs to be copied to every sheet module.
Private Sub Worksheet_Change(ByVal Target As Range)
Dim ws As Worksheet
If Target.Address = "$B$5" Then
For Each ws In ThisWorkbook.Worksheets
If Not ws.Name = Me.Name And Not ws.Name = "Sheet3" Then
If Not ws.Range(Target.Address) = Me.Range(Target.Address) Then
ws.Range(Target.Address) = Me.Range(Target.Address)
End If
End If
Next ws
End If
End Sub
This is fairly easy with activeX comboboxes on the sheets
On the workbook module add the code below to populate the comboboxes
Private Sub Workbook_Open()
With ThisWorkbook
With .Worksheets("Sheet1").ComboBox1
.AddItem "Complete"
.AddItem "Incomplete"
End With
With .Worksheets("Sheet2").ComboBox1
.AddItem "Complete"
.AddItem "Incomplete"
End With
End With
End Sub
On the "Sheet1" Module add
Private Sub ComboBox1_Change()
If Me.ComboBox1 = "Complete" Then
ThisWorkbook.Worksheets("Sheet2").ComboBox1.Value = "Complete"
ElseIf Me.ComboBox1 = "Incomplete" Then
ThisWorkbook.Worksheets("Sheet2").ComboBox1.Value = "Incomplete"
End If
End Sub
On the "Sheet2" Module add
Private Sub ComboBox1_Change()
If Me.ComboBox1 = "Complete" Then
ThisWorkbook.Worksheets("Sheet1").ComboBox1.Value = "Complete"
ElseIf Me.ComboBox1 = "Incomplete" Then
ThisWorkbook.Worksheets("Sheet1").ComboBox1.Value = "Incomplete"
End If
End Sub