If you would like to show multi options opened you should do minimal edition in your "jquery.ui.accordion.js"

Find the beginig of the function "_toggle" in the file jquery.ui.accordion.js
   
    _toggle: function( toShow, toHide, data, clickedIsActive, down ) {
        var self = this,
            options = self.options;
   
Add the following code after the code above:
       
        if (!clickedIsActive) {
            toHide = $( [] );
        }

The accordion should allow opening of multi options at one time.