Preventing ClearContents on Combination of Merged and Unmerged Cells

I'm not sure how to get around merged cells accounting for each cell within the range that is merged, but I'm trying to prevent the user from selecting a combination of cells next to one another and clearing contents.

Sub PreventDeleteMultipleMergedCells()
    
    If Selection.Count = 1 Then
        Selection.ClearContents
    Else
        MsgBox "You cannot delete the contents of multiple selected cells."
    End If
    
End Sub

I came across a public function (see below) in my research, but I'm not sure how to work the output into the sub function that would trigger the MsgBox if the selected cells > 1.

Public Function MergedColumnsCount(c As Range) As Long
    MergedColumnCount = 0
    For i = 1 To c.Columns.Count
        MergeColumnSize = c(i).MergeArea.Columns.Count
        If MergeColumnSize > 1 Then
            i = i + MergeColumnSize - 1
        End If
        MergedColumnCount = MergedColumnCount + 1
    Next i
    MergedColumnsCount = MergedColumnCount
End Function

rng.MergeCells - Determines if the range or style contains merged cells.

Sub CheckSingleCell()
    Dim selectedRange As Range
    Set selectedRange = Selection

    If IsSingleCell(selectedRange) Then
        MsgBox "The selected range consists of only one cell."
    Else
        MsgBox "The selected range consists of multiple cells."
    End If
End Sub


Function IsSingleCell(rng As Range) As Boolean

    ' Check if the selection is a single cell
    If rng.Cells.Count = 1 Then
        IsSingleCell = True
    ' Check if the selection is a single merged cell
    ElseIf rng.MergeCells Then
        IsSingleCell = True
    Else
        IsSingleCell = False
    End If

End Function