Allow only 1 Selection by Group when using multiselect in option groups boxs with plugin https://github.com/silviomoreto/bootstrap-select

exadra37.html

<!-- http://silviomoreto.github.io/bootstrap-select/ -->
<select id="compare" class="selectpicker" data-style="btn-success" data-max-options="2" title="Compare Settings" data-width="25em" multiple>
    <optgroup class="multiple-options" label="Compare"  data-max-options="1">
        <option class="exadra37-1-selection-by-group exadra37-group-compare" title="Compare Daily" selected>Daily</option>
        <option class="exadra37-1-selection-by-group exadra37-group-compare" title="Compare Weekly">Weekly</option>
        <option class="exadra37-1-selection-by-group exadra37-group-compare" title="Compare Monthly">Monthly</option>
    </optgroup>
    <optgroup class="multiple-options" label="Against"  data-max-options="1">
        <option class="exadra37-1-selection-by-group exadra37-group-against" title="Against Previous Week" selected>Previous Week</option>
        <option class="exadra37-1-selection-by-group exadra37-group-against" title="Against Last Year">Last Year</option>
    </optgroup>
</select>
<!-- END -->

exadra37.js

/**
 * @author  Paulo Silva(Exadra37)   <exadra37atgmailpointcom>
 * @package Exadra37\BootstrapSelect
 * @version 1.0.0
 * @since   29/07/2014 - v.1.0.0
 * @link    http://silviomoreto.github.io/bootstrap-select/
 */

$(function() {

    $('.selectpicker').selectpicker();

    // Override default behavior of plugin to allow only 1 selection by Group when using multi-select
    // Caveats:
    //      - Once the plugin don't copy data-type attribute or any other one i end up using dummy class names to achieve the desired result
    //      - The dummy class names have "special" names in order to try to avoid conflicts with classes used in css
    $('.selectpicker').data('selectpicker').$menu.on('click', 'li a', function(e) {

        var selectOnlyOneOptionByGroup = $(this).hasClass('exadra37-1-selection-by-group');

        // Only override the one declared in the html with dummy class "exadra37-1-selection-by-group"
        if(selectOnlyOneOptionByGroup) {

            var isClickTriggeredClass = $(this).hasClass('exadra37-click-triggered');

            var optionGroupClickedClass = $(this).attr('class');

            // only apply the action to the option we have clicked
            // will not apply the action to the clicks triggered inside of this if
            // achieved by injecting a dummy class "exadra37-click-triggered" in the trigered event
            if (!isClickTriggeredClass) {

                var lisSelected = $(this).parent('li').siblings('.selected');

                // loop all parent siblings that have class "selected" and remove it by triggering the click event on it
                // if we only use the jquery method remove class, the button value will not update properly
                $.each(lisSelected, function() {

                    var optionGroupToTriggerClass = $(this).children('a').attr('class');

                    // only apply the action to the parent siblings that belongs to the same group
                    if (optionGroupToTriggerClass == optionGroupClickedClass) {

                        // apply a dummy class so that we only go inside this if this class is not present
                        // trigger the click event on all other parent siblings
                        $(this).children('a').addClass('exadra37-click-triggered').trigger('click');
                    };
                });

            } else {

                // remove the dummy class once we don't need it anymore
                $(this).removeClass('exadra37-click-triggered');
            }
        }
    });
});

Great! It was helpful! Thanks a lot!