Making a merged table for Login-Logout

Here is one way to do this.  Below are 3 M queries with similar data as an example.  To see how it works, just create a blank query, go to Advanced Editor, and replace the text there with the M code below (X3).  The first two are just some example tables like your data.

// call this query "login"
let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMtQ31DcyMDJQ0lEytzIwACIFR18gJ7Q4tcgQSBsaGCjF6qCos0RXZwSkjeDqjPCaZ4ypDsM8kDoTkLpYAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, Time = _t, Username = _t, Param1 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Time", type time}, {"Username", type text}, {"Param1", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Event", each "Login")
in
    #"Added Custom"

//call this query "logout"
let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMtQ31DcyMDJQ0lEytzI0sDIwUHD0BXJCi1OLDIG0oYGBUqwOijqgKmNUhUZA2hSqEMiEIog2I5g2SysjTOPNQLpiAQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, Time = _t, Username = _t, Param1 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Time", type time}, {"Username", type text}, {"Param1", Int64.Type}}),
    #"Filtered Rows" = Table.SelectRows(#"Changed Type", each ([Date] <> null)),
    #"Added Custom" = Table.AddColumn(#"Filtered Rows", "Event", each "Logout")
in
    #"Added Custom"

//call this query what you want
let
    Source = Table.Combine({login, logout}),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Event", type text}}),
    #"Sorted Rows" = Table.Sort(#"Changed Type",{{"Username", Order.Ascending}, {"Date", Order.Ascending}, {"Time", Order.Ascending}}),
    #"Added Index" = Table.AddIndexColumn(#"Sorted Rows", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "ForPivot", each if [Event] = "Login" then [Index] else null),
    #"Filled Down" = Table.FillDown(#"Added Custom",{"ForPivot"}),
    #"Added Custom1" = Table.AddColumn(#"Filled Down", "Records", each #"Filled Down"{[Index]}),
    #"Removed Other Columns" = Table.SelectColumns(#"Added Custom1",{"Event", "ForPivot", "Records"}),
    #"Pivoted Column" = Table.Pivot(#"Removed Other Columns", List.Distinct(#"Removed Other Columns"[Event]), "Event", "Records"),
    #"Expanded Login" = Table.ExpandRecordColumn(#"Pivoted Column", "Login", {"Date", "Time", "Username", "Param1"}, {"Date", "Time", "Username", "Param1"}),
    #"Expanded Logout" = Table.ExpandRecordColumn(#"Expanded Login", "Logout", {"Time", "Param1"}, {"Time.1", "Param1.1"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded Logout",{"ForPivot"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Removed Columns",{{"Date", type date}, {"Time", type time}, {"Username", type text}, {"Param1", Int64.Type}, {"Time.1", type time}, {"Param1.1", Int64.Type}}),
    #"Renamed Columns" = Table.RenameColumns(#"Changed Type1",{{"Time", "Time In"}, {"Time.1", "Time Out"}, {"Param1", "Param1 (in)"}, {"Param1.1", "Param1 (out)"}}),
    #"Reordered Columns" = Table.ReorderColumns(#"Renamed Columns",{"Date", "Username", "Time In", "Time Out", "Param1 (in)", "Param1 (out)"})
in
    #"Reordered Columns"

If this works for you, please mark it as the solution.  Kudos are appreciated too.  Please let me know if not.

Regards,

Pat