Mandatory Field or unable to save based another field having data

Hello Everyone
I have a database that I have created (with the welcomed help of others). In order to save the file I want to make cells mandatory based on data in another cell.
For example if someone adds information to cell C8 then B8 (todays date), E8 (FC Name) and K8 (Status) must have a value. I found this formula which works for B8 but I do not know how to modify it to include E8 and K8. I also needs this formula to repeat for the entire column....spreadsheet has 99 rows.

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)

If Not Sheets("Input").Range("C8") Is Nothing Then
If Sheets("Input").Range("B8") = vbNullString Then
MsgBox "You must enter todays date in Column B. Please Revise", vbOKOnly, "Oops"
Exit Sub
End If
End If

End Sub

...any help is greatly appreciated