Adding 60 onto each day value

Some fake sample data would have helped us understand your case.

In the screen shot below, the blue table is the input in Table1.

The green table is the table from query Result.

Query Table1 imports Table1 into Power Query.

Query Result:

let
    Source = Table1,
    #"Inserted End of Month" = Table.AddColumn(Source, "End of Month", each Date.EndOfMonth([Date]), type date),
    #"Filtered Rows" = Table.SelectRows(#"Inserted End of Month", each ([OpenOrClosed] = "Open")),
    #"Grouped Rows" = Table.Group(#"Filtered Rows", {"End of Month"}, {{"AllData", each Table.AddIndexColumn(_,"Value",60,60), Value.Type(Table.AddColumn(#"Filtered Rows","Value",each 0, Int64.Type))}}),
    #"Expanded AllData" = Table.ExpandTableColumn(#"Grouped Rows", "AllData", {"Date", "OpenOrClosed", "Value"}, {"Date", "OpenOrClosed", "Value"}),
    #"Merged Queries" = Table.NestedJoin(Source,{"Date"},#"Expanded AllData",{"Date"},"AllData",JoinKind.LeftOuter),
    #"Expanded AllData1" = Table.ExpandTableColumn(#"Merged Queries", "AllData", {"Value"}, {"Value"}),
    #"Replaced Value" = Table.ReplaceValue(#"Expanded AllData1",null, each if [Date] = Date.StartOfMonth([Date]) then 0 else null,Replacer.ReplaceValue,{"Value"}),
    #"Restored Type" = Value.ReplaceType(#"Replaced Value",Value.Type(#"Expanded AllData1")),
    #"Sorted Rows" = Table.Sort(#"Restored Type",{{"Date", Order.Ascending}}),
    #"Filled Down" = Table.FillDown(#"Sorted Rows",{"Value"})
in
    #"Filled Down"