Combine two existing contact by AggregationExceptions
ArrayList<ContentProviderOperation> ops0 = new ArrayList<ContentProviderOperation>();
         ops0.add(ContentProviderOperation.newUpdate(ContactsContract.AggregationExceptions.CONTENT_URI)
                 .withValue(ContactsContract.AggregationExceptions.RAW_CONTACT_ID1,ID_main)
                 .withValue(ContactsContract.AggregationExceptions.RAW_CONTACT_ID2,ID_other)
                 .withValue(ContactsContract.AggregationExceptions.TYPE,ContactsContract.AggregationExceptions.TYPE_KEEP_TOGETHER).build());
         try {
             getContentResolver().applyBatch(ContactsContract.AUTHORITY, ops0);
         } catch (Exception e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }

.withValue(ContactsContract.AggregationExceptions.RAW_CONTACT_ID1,ID_main)
.withValue(ContactsContract.AggregationExceptions.RAW_CONTACT_ID2,ID_other)

.withValue(ContactsContract.AggregationExceptions.RAW_CONTACT_ID1,ID_other)
.withValue(ContactsContract.AggregationExceptions.RAW_CONTACT_ID2,ID_main)