diff --git a/themis/importexport/sync.py b/themis/importexport/sync.py
index ff9efad..d6ec50c 100644
--- a/themis/importexport/sync.py
+++ b/themis/importexport/sync.py
@@ -72,6 +72,24 @@ class SyncFromThemis(UtilityView):
 
         return 'OK'
 
+    def create_relation_value_if_needed(self, current_value, intid):
+        if intid is None:
+            return None
+        if current_value is None or current_value.to_id != intid:
+            return RelationValue(intid)
+        return current_value
+
+    def create_relation_value_list_if_needed(self, current_value, intids):
+        if not intids:
+            return []
+        if current_value:
+            current_intids = list(sorted([x.to_id for x in current_value]))
+        else:
+            current_indids = []
+        if current_value is None or current_intids != intids:
+            return [RelationValue(x) for x in intids]
+        return current_value
+
     def sync_deputies(self, timestamp=None):
         deputies = json.load(self.urlopen('%s/@@listDeputies' % self.src_url)) # XXX: add timestamp
 
@@ -102,10 +120,8 @@ class SyncFromThemis(UtilityView):
                                         data.get('birthdate'), '%Y-%m-%d').toordinal())
             else:
                 object.birthdate = None
-            if data.get('polgroup'):
-                object.polgroup = RelationValue(self.get_polgroup_intid(data.get('polgroup')))
-            else:
-                object.polgroup = None
+            self.polgroup = self.create_relation_value_if_needed(self.polgroup,
+                        self.get_polgroup_intid(data.get('polgroup')))
             if data.get('picture'):
                 # this will be an url
                 content = self.urlopen(data.get('picture')).read()
@@ -156,17 +172,17 @@ class SyncFromThemis(UtilityView):
                         title=data.get('title'))
             object = getattr(self.commissions_folder, new_id)
             object.active = data.get('active')
-            if data.get('president'):
-                object.president = RelationValue(self.get_author_intid('deputy:%s' % data.get('president')))
-            if data.get('vicepresidents'):
-                object.vicepresidents = [RelationValue(self.get_author_intid('deputy:%s' % x))
-                                         for x in data.get('vicepresidents')]
-            if data.get('members'):
-                object.members = [RelationValue(self.get_author_intid('deputy:%s' % x))
-                                  for x in data.get('members')]
-            if data.get('substitutes'):
-                object.substitutes = [RelationValue(self.get_author_intid('deputy:%s' % x))
-                                      for x in data.get('substitutes')]
+            object.president = self.create_relation_value_if_needed(object.president,
+                        self.get_author_intid('deputy:%s' % data.get('president')))
+            object.vicepresidents = self.create_relation_value_list_if_needed(
+                    object.vicepresidents,
+                    [self.get_author_intid('deputy:%s' % x) for x in data.get('vicepresidents', [])])
+            object.members = self.create_relation_value_list_if_needed(
+                    object.members,
+                    [self.get_author_intid('deputy:%s' % x) for x in data.get('members', [])])
+            object.substitutes = self.create_relation_value_list_if_needed(
+                    object.substitutes,
+                    [self.get_author_intid('deputy:%s' % x) for x in data.get('substitutes', [])])
             if data.get('competences'):
                 object.competences = data.get('competences')
             notify(ObjectModifiedEvent(object))
@@ -252,13 +268,14 @@ class SyncFromThemis(UtilityView):
                          'orateurs_seance_reponse_orale'):
                 speakers = list(set(speakers + (data.get(attr) or [])))
 
-            object.speakers = [self.get_author_intid(x) for x in speakers]
-            object.speakers = [RelationValue(x) for x in object.speakers if x]
+            speakers_intids = [self.get_author_intid(x) for x in speakers]
+            object.speakers = self.create_relation_value_list_if_needed(
+                    object.speakers, speakers_intids)
 
             reporters = []
-            object.reporters = [self.get_author_intid(x) for x in data.get('rapporteurs') or []]
-            object.reporters = [RelationValue(x) for x in object.reporters if x]
-
+            reporters_intids = [self.get_author_intid(x) for x in data.get('rapporteurs') or []]
+            object.reporters = self.create_relation_value_list_if_needed(
+                    object.reporters, reporters_intids)
 
             if data.get('date_sanction_promulgation'):
                 object.sanction_date = datetime.date.fromordinal(
@@ -334,7 +351,8 @@ class SyncFromThemis(UtilityView):
                     else:
                         continue
                     related_docs.append(self.intids.getId(related_doc))
-                object.related_docs = [RelationValue(x) for x in related_docs if x]
+                object.related_docs = self.create_relation_value_list_if_needed(
+                        object.related_docs, related_docs)
 
             authors_v = None
             if data.get('auteur'):
@@ -349,7 +367,8 @@ class SyncFromThemis(UtilityView):
                 authors_intids = [self.get_author_intid(x) for x in authors_v]
                 if None in authors_intids:
                     log.warn('unknown error in doc %s' % object.id)
-                object.authors = [RelationValue(x) for x in authors_intids if x]
+                object.authors = self.create_relation_value_list_if_needed(
+                        object.authors, authors_intids)
                 object.author_is_government = False
             else:
                 object.authors = None