select2(new DOM) is not displaying in ckeditor.

I am newbie to ckeditor. I have integrated a mathquill package(mathedit) as a plugin in ckeditor.

The package has a plugin.js, It configured as

var pluginName = 'mathedit',
    pluginCmd = 'mathDialog',
    inputFieldId = 'mathedit-latex-input-field-1',
    mathImgClass = 'mathImg',
    runningId = 0;
CKEDITOR.plugins.add( pluginName, {
init: function ( editor ) {
    var iconPath = this.path + 'icons/lambda.png';
    // register dialog-command
    editor.addCommand( pluginCmd, 
        new CKEDITOR.dialogCommand(pluginCmd, {
        // basic ACF-integration
        allowedContent: 'img[src,title,class](mathImg)',
        requiredContent: 'img[src,title,class](mathImg)'
    }));
editor.ui.addButton( pluginName, {
        label : 'Insert science',
        command : pluginCmd,
        toolbar: 'insert',
        icon: iconPath
    });

Now I have added a select2 package in that mathedit plugin, which have a search option. Then search option functionality is working perfectly. But the search results are displaying outside of plugin. As the plugin is a dialog, so outside of plugin is not accessible.

I was going through ASF with plugins. There it is saying that," plugin may also deactivate features which generate HTML code that is not allowed by the configuration". So for that, I have added select2 in allowedContent. But still not working.

allowedContent: 'img[src,title,class](sciImg)(select2)',

and also

allowedContent: 'img[src,title,class](sciImg);select2',

Please help me, as I tried so many thing.

My intput text in plugin is

<input type="text" id="placeSelect" />
$('#placeSelect').select2({
        width: '100%',
        allowClear: true,
        multiple: true,
        maximumSelectionSize: 10,
        placeholder: "Search Chemistry word.",
        data:window.symbol_json//any valid data object

});

Thanks in advance