diff --git a/builder.py b/builder.py
index 6b4cc23..30bdf48 100644
--- a/builder.py
+++ b/builder.py
@@ -117,6 +117,16 @@ class CCEFile():
 
     def parseEntry(self, entry, shared=[]):
         uuid = entry.get('id')
+        duplicate = entry.get('duplicateOf')
+        partOf = self.getEntryID(entry.get('partOf')) if entry.get('partOF') else None
+        
+        if duplicate is not None:
+            print('Found Duplicate Entry')
+            raise DataError(
+                'duplicate_entry',
+                uuid=uuid,
+                entry=entry
+            )
         
         if 'regnum' not in entry.attrib:
             print('Entry Missing REGNUM')
@@ -144,14 +154,19 @@ class CCEFile():
         regs = self.createRegistrations(regnums, regDates)
         existingRec = self.matchUUID(uuid)
         if existingRec:
-            self.updateEntry(existingRec, entryDates, entry, shared, regs)
+            self.updateEntry(existingRec, entryDates, entry, shared, regs, partOf)
         else:
-            self.createEntry(uuid, entryDates, entry, shared, regs)
+            self.createEntry(uuid, entryDates, entry, shared, regs, partOf)
 
     def matchUUID(self, uuid):
         return self.session.query(CCE).filter(CCE.uuid == uuid).one_or_none()
+    
+    def getEntryID(self, uuid):
+        ent = self.session.query(CCE.id).filter(CCE.uuid == uuid).one_or_none()
+        if ent: return ent.id
+        else: return None
 
-    def createEntry(self, uuid, dates, entry, shared, registrations):
+    def createEntry(self, uuid, dates, entry, shared, registrations, partOf):
         titles = self.createTitleList(entry, shared)
         authors = self.createAuthorList(entry, shared)
         copies = CCEFile.fetchText(entry, 'copies')
@@ -186,12 +201,13 @@ class CCEFile():
             authors=authors,
             publishers=publishers,
             lccn=lccn,
-            registrations=registrations
+            registrations=registrations,
+            partOf=partOf
         )
         self.session.add(cceRec)
         print('INSERT', cceRec)
 
-    def updateEntry(self, rec, dates, entry, shared, registrations):
+    def updateEntry(self, rec, dates, entry, shared, registrations, partOf):
         rec.title = self.createTitleList(entry, shared)
         rec.copies = CCEFile.fetchText(entry, 'copies')
         rec.description = CCEFile.fetchText(entry, 'desc')
@@ -218,7 +234,8 @@ class CCEFile():
             authors=authors,
             publishers=publishers,
             lccn=lccn,
-            registrations=registrations
+            registrations=registrations,
+            partOf=partOf
         )
         print('UPDATE', rec)
 
diff --git a/model/cce.py b/model/cce.py
index ed95b1d..ebf9689 100644
--- a/model/cce.py
+++ b/model/cce.py
@@ -42,22 +42,25 @@ class CCE(Core, Base):
     aff_date_text = Column(Unicode)
 
     volume_id = Column(Integer, ForeignKey('volume.id'))
+    parent_cce_id = Column(Integer, ForeignKey('cce.id'))
 
     registrations = relationship('Registration', backref='cce')
     lccns = relationship('LCCN', backref='cce', cascade='all, delete-orphan')
     authors = relationship('Author', backref='cce', cascade='all, delete-orphan')
     publishers = relationship('Publisher', backref='cce', cascade='all, delete-orphan')
+    children_cces = relationship('CCE')
 
     def __repr__(self):
         return '<CCE(regnums={}, uuid={}, title={})>'.format(self.registrations, self.uuid, self.title)
 
-    def addRelationships(self, volume, xml, lccn=[], authors=[], publishers=[], registrations=[]):
+    def addRelationships(self, volume, xml, lccn=[], authors=[], publishers=[], registrations=[], partOf=None):
         self.volume = volume
         self.addLCCN(lccn)
         self.addAuthor(authors)
         self.addPublisher(publishers)
         self.addRegistration(registrations)
         self.addXML(xml)
+        self.setParentCCE(partOf)
     
     def addLCCN(self, lccns):
         self.lccns = [ LCCN(lccn=lccn) for lccn in lccns ]
@@ -92,12 +95,13 @@ class CCE(Core, Base):
             for reg in registrations
         ]
     
-    def updateRelationships(self, xml, lccn=[], authors=[], publishers=[], registrations=[]):
+    def updateRelationships(self, xml, lccn=[], authors=[], publishers=[], registrations=[], partOf=None):
         self.addXML(xml)
         self.updateLCCN(lccn)
         self.updateAuthors(authors)
         self.updatePublishers(publishers)
         self.updateRegistrations(registrations)
+        self.setParentCCE(partOf)
     
     def updateLCCN(self, lccns):
         currentLCCNs = [ l.lccn for l in self.lccns ]
@@ -156,6 +160,9 @@ class CCE(Core, Base):
     def updateReg(self, reg, registrations):
         newReg = CCE.getReg(reg.regnum, registrations)
         reg.update(newReg)
+    
+    def setParentCCE(self, parentID):
+        self.parent_cce_id = parentID
 
     @staticmethod
     def getReg(regnum, newRegs):