diff --git a/backup/moodle2/backup_custom_fields.php b/backup/moodle2/backup_custom_fields.php
index a56ad659e99..ada8306362e 100644
--- a/backup/moodle2/backup_custom_fields.php
+++ b/backup/moodle2/backup_custom_fields.php
@@ -101,3 +101,9 @@ class file_nested_element extends backup_nested_element {
         backup_file_manager::copy_file_moodle2backup($this->backupid, $values);
     }
 }
+
+/**
+ * Implementation of backup_optigroup_element to be used by subplugins stuff.
+ * Split just for better separation and future especialitation
+ */
+class backup_subplugin_element extends backup_optigroup_element { }
diff --git a/backup/moodle2/backup_plan_builder.class.php b/backup/moodle2/backup_plan_builder.class.php
index 4b12efdd1da..5e81d80d218 100644
--- a/backup/moodle2/backup_plan_builder.class.php
+++ b/backup/moodle2/backup_plan_builder.class.php
@@ -30,6 +30,7 @@ require_once($CFG->dirroot . '/backup/moodle2/backup_final_task.class.php');
 require_once($CFG->dirroot . '/backup/moodle2/backup_block_task.class.php');
 require_once($CFG->dirroot . '/backup/moodle2/backup_default_block_task.class.php');
 require_once($CFG->dirroot . '/backup/moodle2/backup_xml_transformer.class.php');
+require_once($CFG->dirroot . '/backup/moodle2/backup_subplugin.class.php');
 require_once($CFG->dirroot . '/backup/moodle2/backup_settingslib.php');
 require_once($CFG->dirroot . '/backup/moodle2/backup_stepslib.php');
 require_once($CFG->dirroot . '/backup/moodle2/backup_custom_fields.php');
diff --git a/backup/moodle2/backup_stepslib.php b/backup/moodle2/backup_stepslib.php
index 0ab76fc2803..e9631b39b25 100644
--- a/backup/moodle2/backup_stepslib.php
+++ b/backup/moodle2/backup_stepslib.php
@@ -75,10 +75,48 @@ class create_taskbasepath_directory extends backup_execution_step {
 
 /**
  * Abtract tructure step, parent of all the activity structure steps. Used to wrap the
- * activity structure definition within the main <activity ...> tag
+ * activity structure definition within the main <activity ...> tag. Also provides
+ * subplugin support for activities (that must be properly declared)
  */
 abstract class backup_activity_structure_step extends backup_structure_step {
 
+    protected function add_subplugin_structure($subpluginname, $element, $multiple) {
+
+        global $CFG;
+
+        // Check the requested subpluginname is a valid one
+        $subpluginsfile = $CFG->dirroot . '/mod/' . $this->task->get_modulename() . '/db/subplugins.php';
+        if (!file_exists($subpluginsfile)) {
+             throw new backup_step_exception('activity_missing_subplugins_php_file', $this->task->get_modulename());
+        }
+        include($subpluginsfile);
+        if (!array_key_exists($subpluginname, $subplugins)) {
+             throw new backup_step_exception('incorrect_subplugin_type', $subpluginname);
+        }
+
+        // Arrived here, subplugin is correct, let's create the optigroup
+        $optigroupname = $subpluginname . '_' . $element->get_name() . '_subplugin';
+        $optigroup = new backup_optigroup($optigroupname, null, $multiple);
+
+        // Get all the optigroup_elements, looking across al the subplugin dirs
+        $elements = array();
+        $subpluginsdirs = get_plugin_list($subpluginname);
+        foreach ($subpluginsdirs as $name => $subpluginsdir) {
+            $classname = 'backup_' . $subpluginname . '_' . $name . '_subplugin';
+            $backupfile = $subpluginsdir . '/backup/moodle2/' . $classname . '.class.php';
+            if (file_exists($backupfile)) {
+                require_once($backupfile);
+                $backupsubplugin = new $classname($subpluginname, $name);
+                // Add subplugin returned structure to optigroup (must be optigroup_element instance)
+                if ($subpluginstructure = $backupsubplugin->define_subplugin_structure($element->get_name())) {
+                    $optigroup->add_child($subpluginstructure);
+                }
+            }
+        }
+        // Finished, add optigroup to element
+        $element->add_child($optigroup);
+    }
+
     protected function prepare_activity_structure($activitystructure) {
 
         // Create the wrap element
diff --git a/backup/moodle2/backup_subplugin.class.php b/backup/moodle2/backup_subplugin.class.php
new file mode 100644
index 00000000000..2b2c7985c3d
--- /dev/null
+++ b/backup/moodle2/backup_subplugin.class.php
@@ -0,0 +1,70 @@
+<?php
+
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * @package    moodlecore
+ * @subpackage backup-moodle2
+ * @copyright  2010 onwards Eloy Lafuente (stronk7) {@link http://stronk7.com}
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+/**
+ * Class implementing the subplugins support for moodle2 backups
+ *
+ * TODO: Finish phpdocs
+ */
+abstract class backup_subplugin {
+
+    protected $subplugintype;
+    protected $subpluginname;
+
+    public function __construct($subplugintype, $subpluginname) {
+        $this->subplugintype = $subplugintype;
+        $this->subpluginname = $subpluginname;
+    }
+
+    public function define_subplugin_structure($connectionpoint) {
+
+        $methodname = 'define_' . $connectionpoint . '_subplugin_structure';
+
+        if (method_exists($this, $methodname)) {
+            return $this->$methodname($connectionpoint);
+        }
+
+        return false;
+    }
+
+    /**
+     * Factory method that will return one backup_subplugin_element (backup_optigroup_element)
+     * with its name automatically calculated, based one the subplugin being handled (type, name)
+     */
+    protected function get_subplugin_element($connectionpoint, $final_elements = null, $conditionparam = null, $conditionvalue = null) {
+        // Something exclusive for this backup_subplugin_element (backup_optigroup_element)
+        // because it hasn't XML representation
+        $name = 'optigroup_' . $this->subplugintype . '_' . $this->subpluginname . '_' . $connectionpoint;
+        return new backup_subplugin_element($name, $final_elements, $conditionparam, $conditionvalue);
+    }
+
+    /**
+     * Simple helper function that suggests one name for the main nested element in subplugins
+     * It's not mandatory to use it but recommended ;-)
+     */
+    protected function get_recommended_name($connectionpoint) {
+        return 'subplugin_' . $this->subplugintype . '_' . $this->subpluginname . '_' . $connectionpoint;
+    }
+
+}
diff --git a/backup/util/structure/base_optigroup.class.php b/backup/util/structure/base_optigroup.class.php
index 67a01e30b5b..e3f0dfd1815 100644
--- a/backup/util/structure/base_optigroup.class.php
+++ b/backup/util/structure/base_optigroup.class.php
@@ -131,7 +131,7 @@ abstract class base_optigroup extends base_nested_element {
      * Recalculate all the used elements in the optigroup, observing
      * restrictions and passing the new used to outer level
      */
-    function add_used($element) {
+    protected function add_used($element) {
         $newused = array();
         // Iterate over all the element useds, filling $newused and
         // observing the multiple setting