Index: lib/filterStorage.js
===================================================================
--- a/lib/filterStorage.js
+++ b/lib/filterStorage.js
@@ -123,16 +123,31 @@
    * @type {number}
    */
   get subscriptionCount()
   {
     return this.knownSubscriptions.size;
   }
 
   /**
+   * Adds any subscriptions to which a filter belongs to the filter.
+   * @param {Filter} filter
+   */
+  addSubscriptionsToFilter(filter)
+  {
+    for (let subscription of this.subscriptions())
+    {
+      if (subscription.filters.indexOf(filter) != -1)
+        filter.addSubscription(subscription);
+    }
+
+    filter.subscriptionsAssigned = true;
+  }
+
+  /**
    * Finds the filter group that a filter should be added to by default. Will
    * return <code>null</code> if this group doesn't exist yet.
    * @param {Filter} filter
    * @returns {?SpecialSubscription}
    */
   getGroupForFilter(filter)
   {
     let generalSubscription = null;