How do I manually set tnid when migrating nodes?
You want to give the node a language, and set the source node in the translation_source key:

$node-&gt;language = 'es';
$node-&gt;translation_source = node_load(66);


Reference: https://api.drupal.org/api/drupal/modules!translation!translation.module/function/translation_node_prepare/7