--- a/farolluz/document.py	Mon Oct 27 12:29:37 2014 +0100
+++ b/farolluz/document.py	Mon Oct 27 12:29:56 2014 +0100
@@ -306,13 +306,22 @@
                 item._productids.remove(old)
                 item._productids.append(new)
 
+    def mentionsGroupId(self, groupid):
+        for vulnerability in self._vulnerabilities:
+            for item in vulnerability.mentionsGroupId(groupid):
+                yield item
+
     def isGroupOrphan(self, groupid):
         """ Returns if a group can be safely deleted """
-        for vulnerability in self._vulnerabilities:
-            if vulnerability.isMentioningGroupId(groupid):
-                return False
+        for _ in self.mentionsGroupId(groupid):
+            return False
         return True
 
+    def changeGroupID(self, old, new):
+        for item in self.mentionsGroupId(old):
+            item._groupids.remove(old)
+            item._groupids.append(new)
+
     def isProductTreeOrphan(self):
         """ Difference with the previous method is that we don;t care about
         inter-producttree references """