SQL 2008

Hello,
I'm using this Stored Procedure for one of my clients.

Select report from (
Select  
      'DETAIL,' + case when ao.Instructions  like 'Return%' then 'Y' else 'N' end
        + ao.DeliveryCompanyName + ',' + ao.POD +
      + Case ao.StatusID
                   WHEN 4      THEN 'X6'  
                   WHEN 5      THEN 'X4'  
                   else ''
                   end
+ 'NS'+ ',' + case WHEN (coalesce(CONVERT(char(8), si.ShipmentDate, 112),'')) Like  '' then coalesce(CONVERT(char(8), ao.OrderDate, 112),'') else coalesce(CONVERT(char(8), si.ShipmentDate, 112),'')  end
+ case WHEN (COALESCE(RIGHT (si.BillingTimeSTamp ,6), ' ')) Like  '' then (Select replace(convert(varchar, getdate(),108),':','')) else COALESCE(RIGHT (si.BillingTimeSTamp ,6), ' ') end
+ coalesce(CONVERT(char(20), (Select Name From Drivers where DriverNumber = ao.PickupDriver)),'')
      AS [Report]
                  ,ROW_NUMBER() over (partition by
                  si.BSN , ao.Reference order by  si.BillingTimeSTamp) as rn
From Database01.[dbo].[ActiveOrders]  as ao
LEFT join Database02.[dbo].[ScanItem] as si
on si.CCOrderNo = ao.Orderno
where ao.Accountnumber = 12345  AND ao.Instructions  like 'Return%'
) as x
where rn=1

I need to add another case / if :into
      + Case ao.StatusID
                   WHEN 4      THEN 'X6'  
                   WHEN 5      THEN 'X4'  
                   else ''
                   end
CASE  ao.Instructions like '%NO ONE HOME%' then ao.StatusID = 'AP'

Any help is appreciated.