i think so, this will work out

For Each myCell In myRng.Cells
With myCell
.Offset(0, 2).Validation.Delete
If IsNumeric(.Value) _
And .Text Like "#.#" Then
With .Offset(0, 2)
If IsEmpty(.Value) Then
.Value = ""
With .Validation
.Add Type:=xlValidateList, _
AlertStyle:=xlValidAlertStop, _
Operator:=xlBetween, Formula1:="Yes,No"

End With
End If
End With
End If
End With
Next myCell

Next