Update existing field collections with Migrate module How can I update existing field collection entities using Migrate module? I wasn't able to find any examples at the official documentation page, nor anywhere else.

When I'm migrating nodes, I can do something like:

$this-&gt;addFieldMapping('nid', 'nid');
$this-&gt;systemOfRecord = Migration::DESTINATION;


What's the alternative in this case?
There's no current support in field_collection for this (a destination plugin must explicitly support Migration::DESTINATION, merging mapped fields with pre-existing values for the unmapped fields). I'd suggest submitting a feature request at https://www.drupal.org/project/issues/field_collection.