Merging 4 tables that also include Union All

I have this code WHICH IS JOIN OF 3 TABLES,    SELECT   [Provider] AS Publisher ,[Price_Rate] ,[Source_ID] ,Media.Date ,Media.Impressions ,Media.Clicks ,'0' AS [Opt-buyers] ,'0' AS [Completed buyers] ,Media.accounting FROM [dbo].[budget]  AS BUDGET  LEFT JOIN  (    SELECT CASE WHEN [Ad_Set_Name] LIKE 'tw_%'    THEN'twitter'    WHEN [Ad_Set_Name] LIKE 'IN_%'   THEN 'insta'    ELSE '?'       END AS Publisher   ,CAST([Day] AS Date) AS Date   ,SUM(CAST([Impressions] AS INT)) AS Impressions   ,SUM(CAST([Link_Clicks] AS INT)) AS Clicks   ,SUM(CAST([Amount_Spent__USD_] AS money)) AS Spend   FROM [dbo].[twitter]   Group by Day,[Ad_Set_Name]     UNION ALL      SELECT CASE WHEN [Site__PCM_] = 'acuits.com'     THEN 'acqt'      WHEN [Site__PCM_]= 'PulsePoint'      THEN 'plpt'     WHEN [Site__PCM_] = 'SRAX'     THEN 'srax'     ELSE [Site__PCM_]     END AS Publisher     ,CAST(Date AS Date) AS Date     ,SUM(CAST(impressions AS INT)) AS Impressions      ,SUM(CAST(clicks AS INT)) AS Clicks     ,SUM(CAST(media_cost AS money)) AS Spend    FROM [dbo] [pcm]    Group by [Site__PCM_]   ,Date   ) AS new_sources_budget  ON BUDGET.Source_ID = Media.Publisher   WHERE source_id IS NOT NULL    and I'm trying to join another table **called Email** to what's this code is currently providing, but    I'm  having tough time passing thus far. the goal is to add this code     SELECT    SUM(CAST(_Send2 AS INT)) AS [Email Sent]  ,SUM(CAST(_Open2 AS INT)) AS [Email Open]  ,SUM(CAST(Click2 AS INT)) AS [Email Click] FROM [dbo].[behaviour] Group by _Send2,_Open2,Click2   any help will be appreciated.