VBA Excel find and replace WITHOUT replacing items already replaced

Question

I am looking to make an excel script that can find and replace data, but for the love of everything I cannot figure out how to write it.

Situation:

A-----------B-----------C

Cat-------Dog------Banana

Dog------Fish------Apple

Fish------Cat-------Orange

So the macro would look at the data in a cell in column B, then look at the adjacent cell in column C, and replace all instances of that data in column A with what if found in C. So the results would be:

A---------------B-----------C

Orange------Dog------Banana

Banana------Fish------Apple

Apple--------Cat-------Orange

But that's not all, I would like it to not change cells in A that already have been changed once! (I'm trying this with changing the background colour)

Any help? I am at a complete loss.

EDIT:

Okay I found out how to do the easy part (replacing), but I cannot find out how to not change cells that already have been changed once. Here is my code:

Sub multiFindNReplace()
    Dim myList, myRange
    Set myList = Sheets("sheet1").Range("A2:B3") 'two column range where find/replace pairs are
    Set myRange = Sheets("sheet1").Range("D2:D5") 'range to be searched
    For Each cel In myList.Columns(1).Cells
    myRange.Replace what:=cel.Value, replacement:=cel.Offset(0, 1).Value, ReplaceFormat:=True
    Next cel
End Sub

As far as I can tell, ReplaceFormat:=True doesn't do anything ;/ so items that already have been replaced once still are being replaced! Is there a way to somehow make this work?

Answer 1

Here's the answer using your recommendation with color as a one-time limiter:

Sub Replace_Once()

'Find last row using last cell in Column B
LastRow = Range("B" & Rows.Count).End(xlUp).Row

'Clear colors in Column A
Range("A1:A" & LastRow).Interior.ColorIndex = xlNone

'Look at each cell in Column B one at a time (Cel is a variable)
For Each Cel In Range("B1:B" & LastRow)
    'Compare the cell in Column B with the Value in Column A one at a time (C is a variable)
    For Each C In Range("A1:A" & LastRow)
        'Check if the Cell in Column A matches the Cell in Column B and sees if the color has changed.
        If C.Value = Cel.Value And C.Interior.Color <> RGB(200, 200, 200) Then
            'Colors the cell
            C.Interior.Color = RGB(200, 200, 200)
            'Updates the value in Column A with the cell to the right of the Cell in Column B
            C.Value = Cel.Offset(0, 1).Value
        End If
    Next
Next

'Uncomment the line below to remove color again
'Range("A1:A" & LastRow).Interior.ColorIndex = xlNone

End Sub