SQL Query modification to create a tally of Result based on result of tally of last event on the same date

I have a query that captures the events that give a date and time, I group them into a related DayStartDate so some events that are on the next calendar date are classed as the previous day. What I need to do is add a column that creates a running tally. So on each event it looks at the previous event on the same day and returns a value of the previous Tally result in its own column and the new result in the Result Column I have shown a cutdown version of what the SQL query shows now and what I am trying to achieve. This is my current query and I am looking at how to modify this or how to create a new table if need be that looks at this table and create a running Tally column based on the grouped DayStartDate at each indivdual event based on the EndDate SELECT c.*, YEAR([login to view URL]) * 10000 + MONTH([login to view URL]) * 100 + DAY([login to view URL]) AS DateID, DATEPART(hh, [login to view URL]) * 10000 + DATEPART(mi, [login to view URL]) * 100 + DATEPART(ss, [login to view URL]) AS TimeId, 42.5 AS Payload, CASE WHEN [login to view URL] != LAG([login to view URL]) OVER (ORDER BY [login to view URL], [login to view URL]) THEN CAST('00:00:00' AS time) WHEN [login to view URL] != LAG([login to view URL]) OVER (ORDER BY [login to view URL], [login to view URL]) THEN CAST('00:00:00' AS time) WHEN LAG([login to view URL]) OVER (ORDER BY [login to view URL], [login to view URL]) IS NULL THEN CAST('00:00:00' AS time) WHEN [login to view URL] != LAG([login to view URL]) OVER (ORDER BY [login to view URL], [login to view URL]) THEN CAST('00:00:00' AS time) ELSE CAST(CONVERT(varchar(22), [login to view URL] - LAG([login to view URL]) OVER (ORDER BY [login to view URL], [login to view URL]), 114) AS time) END AS Duration FROM (SELECT b.*, CASE WHEN CAST([login to view URL] AS time) BETWEEN '00:00:00.000' AND '07:14:59.900' THEN CAST(CONVERT(date, [login to view URL] - 1) AS date) ELSE CAST(CAST([login to view URL] AS date) AS date) END AS DayStartDate, CASE WHEN (CAST([login to view URL] AS time) BETWEEN '00:00:00.000' AND '07:14:59.900') OR (CAST([login to view URL] AS time) BETWEEN '19:14:59.900' AND '23:59:59.900') THEN 1 ELSE 0 END AS ShiftNumber FROM (SELECT [login to view URL], [login to view URL] AS EventName, [login to view URL], [login to view URL], dateadd(HH, DATEPART(TZ, [login to view URL] AT time Zone [login to view URL]) / 60, [login to view URL]) AS EndDate, [login to view URL], [login to view URL] FROM Events e INNER JOIN EventDefs ed ON [login to view URL] = [login to view URL] INNER JOIN Segments s ON [login to view URL] = [login to view URL] INNER JOIN DriversAll da ON [login to view URL] = [login to view URL] INNER JOIN Trips t ON t .TripId = [login to view URL] INNER JOIN VehiclesAll va ON [login to view URL] = t .VehicleId INNER JOIN Sites si ON [login to view URL] = [login to view URL] WHERE [login to view URL] = 1381) b) c