Set Structure Parent when creating Entry in Plugin
This question is old, but the solution is: 

// look up parent with a ElementCriteriaModel

$parentCriteria = craft()-&gt;elements-&gt;getCriteria(ElementType::Entry);

$parentCriteria-&gt;search  = 'slug:'.$parentSlug; // whatever you have

$parent = $parentCriteria-&gt;find()[0];

$entry = new EntryModel();
$entry-&gt;sectionId = $section;

$entry-&gt;parentId = $parent-&gt;id; 

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