New "C" (which works).  Awesome.  Many thanks.

USE [W_SE-MFG]
GO
/****** Object: UserDefinedFunction [dbo].[QtyOnHandNoExcl]  Script Date: 2017-10-12 09:57:22 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER FUNCTION [dbo].[QtyOnHandNoExcl]
(@SC nVarChar(30), @Wh nVarchar(3), @CIE varchar(1))
RETURNS Decimal(8,3) 
AS 
BEGIN
DECLARE @ret Decimal(8,3)
SELECT @ret = CASE @CIE
WHEN 'K' THEN
  (SELECT SUM(QtyOnHand1) 
  FROM SysproSStar.dbo.InvMultBin p
  WHERE p.StockCode = @SC
   AND p.Warehouse = @Wh
        AND NOT p.Note Like 'EXCL%')
WHEN 'N' THEN
  (SELECT SUM(QtyOnHand1) 
  FROM SysproSStarNZ.dbo.InvMultBin p
  WHERE p.StockCode = @SC
   AND p.Warehouse = @Wh
        AND NOT p.Note Like 'EXCL%')
WHEN 'O' THEN
  (SELECT SUM(QtyOnHand1) 
  FROM SysproSStarAust.dbo.InvMultBin p
  WHERE p.StockCode = @SC
   AND p.Warehouse = @Wh
        AND NOT p.Note Like 'EXCL%')
END;
RETURN(@ret);
END;