How to Convert New Sales Territory/Rep Data Table with Single Date "Event" Rows

You can adjust dt to modify it to your desired date, or a dynamic date.

Hi zwyatt, another solution I could work out using Power Query. Thanks. I'll attach the file link. Have a look if that is what you intend to do with your query.
https://docs.google.com/spreadsheets/d/1a3q1IxlqHrM_Jgajq6B0zOkyni2vLFV9/edit?usp=sharing&ouid=104752674875039603034&rtpof=true&sd=true

Another Method:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUTI2MQWSZvqG+kYGRqZKsToQYXMLS7CwKULYCChgYgpVbgwVjwUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [TerritoryId = _t, EmployeeId = _t, StartDate = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{
        {"TerritoryId", Int64.Type}, {"EmployeeId", Int64.Type}, {"StartDate", type date}}),

//Could be today or any other date
/* Because of the subtraction to get Duration.Days, setting this
    as today will result in the proper calculations below*/
    Yesterday=Date.From(DateTime.FixedLocalNow()),

#"Grouped Territory" = Table.Group(#"Changed Type", {"TerritoryId"}, {
    {"Dates", (t)=> [a=List.Generate(
                        ()=>[a=List.Dates(t[StartDate]{0},
                                        Duration.Days(
                                            ((t[StartDate]{1}?)??Yesterday)-
                                            t[StartDate]{0}),
                                        #duration(1,0,0,0)),idx=0],
                        each [idx] < Table.RowCount(t),
                        each [a=List.Dates(t[StartDate]{[idx]+1},
                                        Duration.Days(
                                            ((t[StartDate]{[idx]+2}?)??Yesterday)-
                                            t[StartDate]{[idx]+1}),
                                        #duration(1,0,0,0)),idx=[idx]+1],
                        each[a]),
                     b=Table.FromColumns(
                          {t[EmployeeId]}
                         & {a}, type table[EmployeeId=Int64.Type,StartDate={date}]),
                     c= Table.ExpandListColumn(b,"StartDate")][c],
                            type table[EmployeeId=Int64.Type, StartDate=date]
                  }}),
    #"Expanded Dates" = Table.ExpandTableColumn(#"Grouped Territory", "Dates", {"EmployeeId", "StartDate"})
in
    #"Expanded Dates"

Source

Results