Filter with dax function

I have a report in Power bi where I show information from different countries, when I select a city it shows me the information from only that country, but I want it to make a sum of the information from the last quarter when no city is selected.
But I already have a dax function and I would just like to add that parameter

INDU_INVENTARIO = 
/*Variables para seleccionar el idiona*/
VAR Seleccion = SELECTEDVALUE(IDIOMAS[Idioma])

/*Variables para encontrar el ultimo registro en base a la columna de fecha y el valor buscado */
var _lastDateMetro = MAXX(FILTER(Industrial_Latam,NOT(ISBLANK(Industrial_Latam[Inventario Industrial (m²)]))),Industrial_Latam[Fecha])
var _lastDateSQF = MAXX(FILTER(Industrial_Latam,NOT(ISBLANK(Industrial_Latam[Inventario Industrial (sqf)]))),Industrial_Latam[Fecha])

/*Varibles donde se guarda el ultimo valor ecncontrado*/
var Metro = MAXX(FILTER(Industrial_Latam,Industrial_Latam[Fecha]=_lastDateMetro),Industrial_Latam[Inventario Industrial (m²)])
var SQF = MAXX(FILTER(Industrial_Latam,Industrial_Latam[Fecha]=_lastDateMetro),Industrial_Latam[Inventario Industrial (sqf)])

Var SUM_INV = MAXX(FILTER(Industrial_Latam,Industrial_Latam[Fecha]=_lastDateMetro),SUM(Industrial_Latam[Inventario Industrial (sqf)]))

Var Formato =
SWITCH (
    TRUE,
    Seleccion = "ESP", Metro,
    Seleccion = "ENG", SQF,
    SUM_INV
    )
return Formato

How could I add that parameter while respecting the other conditions?