Start Date for Fiscal Months for RETURN/ ROW Approach

Hello everybody!

I am using a RETURN-ROW approach for developing an individual calendar.

This calendar approach is structured like this:

Calendar = 
VAR BaseCalendar =
    CALENDAR ( DATE ( 2020; 1; 1 ); DATE ( 2020; 12; 31 ) )
RETURN
    GENERATE (
        BaseCalendar;
        VAR BaseDate = [Date]
        VAR Year =
            YEAR ( BaseDate )
        VAR MonthNumber =
            MONTH ( BaseDate )
        VAR WeekNumber =
            WEEKNUM ( BaseDate )
        VAR FWeek =
            WEEKNUM ( BaseDate; 21 )
        RETURN
            ROW (
                "Day"; BaseDate;
                "Year"; Year;
                "Month Number"; MonthNumber;
                "Month"; FORMAT ( BaseDate; "mmmm" );
                "Year Month"; FORMAT ( BaseDate; "yyyy-mm" );
                "Day of Week"; FORMAT ( BaseDate; "dddd" );
                "Day of Week Short"; FORMAT ( BaseDate; "ddd" );
                "Week"; WeekNumber;
                "Year-Week"; Year & "-" & WeekNumber;
                "Fiscal Week"; FWeek;
                "Fiscal Month Short"; SWITCH (
                    TRUE ();
                    FWeek IN { 1; 2; 3; 4 }; "Jan";
                    FWeek IN { 5; 6; 7; 8 }; "Feb";
                    FWeek IN { 9; 10; 11; 12; 13 }; "Mar";
                    FWeek IN { 14; 15; 16; 17 }; "Apr";
                    FWeek IN { 18; 19; 20; 21 }; "May";
                    FWeek IN { 22; 23; 24; 25; 26 }; "Jun";
                    FWeek IN { 27; 28; 29; 30 }; "Jul";
                    FWeek IN { 31; 32; 33; 34 }; "Aug";
                    FWeek IN { 35; 36; 37; 38; 39 }; "Sep";
                    FWeek IN { 40; 41; 42; 43 }; "Oct";
                    FWeek IN { 44; 45; 46; 47 }; "Nov";
                    FWeek IN { 48; 49; 50; 51; 52; 53 }; "Dec"
            )
    )

Now I would like to add the Start Date for each Fiscal Month into this approach.

Is there any chance to include a calculation for this within the code above?