How to properly bind kendo multiselect with knockout using ajax - ajax

Question

I've been working on this for days and finally have a partially working solution, but it doesnt feel quite right. In fact, i'm not sure any of this is right.
My problem is three fold:
generating the filter value in the read function doesnt seem right. I feel like i should be able to bind the multiselects text value or something and use that in the function,
the filter stops processing if i keep typing characters beyond the minLength setting. If i type "cha" the ds fetches "Charles" and "Chad". But if i continue typing and enter "chad", the filter still shows "Charles".
names already selected in the "value" property continue to display in subsequent searches. So if i select "Charles", then i select "Tim", then i type "cha", "Charles" will show up on the list again. But because he's already selected he should not appear on the list.
I'm using the kendo-knockout js, here's what i have so far:
<select data-bind="kendoMultiSelect: { dataSource: ds, autoBind: false, change:'filterTypeOnChanged', search: relatesSearch, minLength: 3, filter:'contains', value: selectedPersons, dataTextField:'PersonName'}"></select>
And here's the datasource (ds) that i'm binding to. (it's in typescript, so hopefully that wont hang anybody up).
ds = new kendo.data.DataSource({
serverFiltering: true
, type: 'json'
, transport: {
read: (options) => {
var srch: string;
debugger;
if (options.data[0] != undefined)
srch = options.data[0].value;
else
srch = options.data.filter.filters[0].value;
jQuery.ajax({
url: "/Person/GetPersons",
cache: false,
dataType: "json",
async: true,
data: JSON.stringify({ textToBeSearched: srch }),
type: "POST",
contentType: 'application/json, charset=utf-8',
processData: false,
success: result => {
options.success(result.data);
},
error: function (e) {
debugger;
console.log(e);
}
});
}
}
});