Better create start date and end date parameter and then create calc.
use this calc in all datasource and apply in filter
Start date and end date formula with auto update?
IF [Filter ON/OFF]="OFF" THEN [date] ELSEIF [date]<[End date] AND [date]>[Start date] THEN [date] END
What You think about Bland Data by dataset "Czas"
In date1 may be the date that is not in Data2 but in Czas exists every date (from Data1 and Data2) and if I blend Data1 with Czas and Data2 with czas i Can add one Filter on Date dimension in Czas.
But if I do this - records shows * and only one sheet works with filter.
I heve two worksheet Data1WS with Data1 and Data2WS with Data2 I neet to shows all this worksheet with one dashboard and filtered it by one filter - date.