JQuery Droppable in Drop-Function wait until Button is klicked

Question

i use sortable's & Droppables to receive elements from a draggable list. As soon as the update function is executed a modal opens. I want to achieve that the update function is interrupted and waits until a button is clicked in the modal. I have no idea how to achieve this. Thanks a lot. This is my Droppable-List:

$("#myUL2").droppable({
    accept: "#myUL li",
    drop: function(event, ui) {
        //open Modal
        $('#myModal').modal('toggle');            
        //wait until Button in Modal is klicked
        //More Code
}

This is my Button in the Modal:

$(".baugruppe").click(function() {
    //things need to be done before the drop function continues
});