Combining several line items into one column in PowerQuery

If you need to keep the columns that indicate the individual shift durations that make up the actual sum you can use the following code.

let
Source = 
Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8srPyFMIzs0syVDSUTI01vUqzdM1MgayHZOT80vzSjLz0oEcUz1TIGmhFKsTrQRkQJABWBAshmqKCQ5TLPWMEMYoAFkwbKhnYgxmYpplisMsIz0zc+xmwQ1CFjXWM8BlgxkOG0z0zHHYAPY3ph0GEO8BJWIB", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"LEGAL NAME" = _t, DATE = _t, POSITIONS = _t, #"SHIFT DURATION" = _t, #"SCH. SHIFT DURATION" = _t]),
changeDataTypes = 
Table.TransformColumnTypes(Source,{{"LEGAL NAME", type text}, {"DATE", type date}, {"POSITIONS", type text}, {"SHIFT DURATION", type number}, {"SCH. SHIFT DURATION", Int64.Type}}),
replaceNulls = 
//replace blank spaces with null to allow fill down
Table.ReplaceValue(changeDataTypes,"",null,Replacer.ReplaceValue,{"LEGAL NAME", "POSITIONS"}),
replaceNulls1 = 
Table.ReplaceValue(replaceNulls," ",null,Replacer.ReplaceValue,{"LEGAL NAME", "POSITIONS"}),
fillDownColumns = 
//fill down to replace blank spaces and allow grouping
Table.FillDown(replaceNulls1,{"LEGAL NAME", "DATE", "POSITIONS", "SCH. SHIFT DURATION"}),
//group by all columns except SHIFT DURATION, choosing all rows (no aggregation)
groupRows = 
Table.Group(fillDownColumns, {"LEGAL NAME", "DATE", "POSITIONS", "SCH. SHIFT DURATION"}, {{"innerTable", each _, type table [LEGAL NAME=nullable text, DATE=nullable date, POSITIONS=nullable text, SHIFT DURATION=nullable number, SCH. SHIFT DURATION=nullable number]}}),
//select only the SHIFT DURATION column in the inner tables 
addGroupedTable = 
Table.TransformColumns(groupRows, {"innerTable", each Table.SelectColumns(_, "SHIFT DURATION")}),
//add column that sums SHIFT DURATION to get actual time worked
addActualColumn = 
Table.AddColumn(addGroupedTable, "ACTUAL", each List.Sum([innerTable][SHIFT DURATION]), type number),
//transpose the inner tables (rows to columns)
transposeInnerTable = 
Table.TransformColumns(addActualColumn, {"innerTable", each Table.Transpose(_)}),
//create a column of lists (needed to build the inner table expansion)
addListCount = 
Table.AddColumn(transposeInnerTable, "listCount", each Table.ColumnNames([innerTable])),
//get distinct list of column names (used in expansion and renaming of columns)
getDistinctList = 
List.Distinct(List.Combine(addListCount[listCount])),
//convert the list to a table in order to manipulate the list values
convertListToTable = 
Table.FromList(getDistinctList, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
//replace the 'Column' value with 'SHIFT DURATION' (for renaming of expanded columns)
replaceColumnValue = 
Table.ReplaceValue(convertListToTable,"Column","SHIFT DURATION",Replacer.ReplaceText,{"Column1"}),
//convert the table back into a list
convertToList = 
replaceColumnValue[Column1],
//create a list of lists for renaming of expanded columns
createRenamingList = 
List.Zip({getDistinctList, convertToList}),
//expand the inner table using the created list (getDistinctList) to expand all possible columns
expandInnerTable = 
Table.ExpandTableColumn(addListCount, "innerTable", getDistinctList, getDistinctList),
//rename the columns using the created list of lists (createRenamingList)
renameColumns = 
Table.RenameColumns(expandInnerTable,createRenamingList),
//remove un-needed column
removeColumn = 
Table.RemoveColumns(renameColumns,{"listCount"})
in
removeColumn