Power BI Embedded: multiple filter selection, what if a user doesn't select a form value

Hello Team:

We have the following problem:

Whe are using a asp.net core 3 webapp, we are embeddind every visual on the webpage, about 20.

Thanks to you we managed to set filters to every visual but we have the following problems:

1) what if they select multiple variables on one checkbox selector , how do we send the data in one json selection?

2) What if they don't select one selector? we tried sending ["default"], ["isblank"] and only the selector, selected filtered it but the one not selected should show all values selected like in the powerbi.

3) Click default and return to the default values all visuals.

4) If the user wants to save a filter how can we achieve that?

Our code goes as follows:

function ReplaceFilters() {
var a = $("#In1").val();
var b = $("#In2").val();
var txt = $("#myselect1").val();
const filterList = [{
$schema: "http://powerbi.com/product/schema#basic",
target: {
table: "tCalendarioNestleN",
column: "SemanaNestle"
},
logicalOperator: "And",
conditions: [{
operator: "GreaterThanOrEqual",
value: a
}, {
operator: "LessThanOrEqual",
value: b
}]
},
{
$schema: "http://powerbi.com/product/schema#basic",
target: {
table: "tProductos",
column: "cveCategoria"
},
operator: "In",
values: ["All"]
}];