How to create a new relationship between modules from create.js

Hi everyone,

I have a custom code to multi attach files on Cases module. I need to create a relationship with notes (for each for the files selected per input file multiple) once save button clicked. My code on 'create.js' file is:

({
    extendsFrom: 'CreateView',

    initialize: function(options) {
        this._super('initialize', [options]);
        controller = this;
        this.on("render", this.append_attachments_button, this);
        this.context.on('button:save_button:click', this.save_button_click, this);
    },
    // Append input type file and text-area to files info
    append_attachments_button: function() {
        var element = controller.model.get('tct_multi_attach_c');
        var id = $(element).attr('id');
        $("#" + id).empty();
        var controls_append = '<input type="file" id="button_files" multiple /> <br>';
        controls_append += '<textarea id="info_attachments" style="resize:none;background-color:white; color:black; height:80px;" readonly></textarea>';
        $("#" + id).append(controls_append);
        $("#button_files").on('change', this.button_files_change);
    },
    // Populate text area with file's name
    button_files_change: function() {
        $("#info_attachments").val(fname);
        var fi = document.getElementById('button_files');
        if (fi.files.length > 0) {
            for (var i = 0; i <= fi.files.length - 1; i++) {
                var fname = fi.files.item(i).name;
                var fsize = fi.files.item(i).size;
                console.log(fname + " - " + fsize + " bytes");
                if ($("#info_attachments").val() != "")
                    $("#info_attachments").val($("#info_attachments").val() + "\n" + fname);
                else
                    $("#info_attachments").val(fname);
            }
        } else {
            console.log('Please select a file.');
        }
    },

    save_button_click: function() {
        console.log("Save clicked");
        var fi = document.getElementById('button_files');
        if (fi.files.length > 0) {
            for (var i = 0; i <= fi.files.length - 1; i++) {
                var fname = fi.files.item(i).name;
                var fsize = fi.files.item(i).size;
                console.log(fname + " - " + fsize + " bytes");
                // Need to create here the relationship between the new Cases record created with Notes module and upload the current file to respect directory.
                var xmlHttpRequest = new XMLHttpRequest();
                var file = fi.files.item(i);
                var fileName = fname;
                var target = fname
                var mimeType = fname.toString().split('.')[fname.toString().split('.').length - 1];
                xmlHttpRequest.open('POST', target, true);
                xmlHttpRequest.setRequestHeader('Content-Type', mimeType);
                xmlHttpRequest.setRequestHeader('Content-Disposition', 'attachment; filename="' + fileName + '"');
                xmlHttpRequest.send(file);
            }
        }
    }
})
Someone knows how can I make it?
Thak you.