diff --git a/forms/TreeDropdownField.php b/forms/TreeDropdownField.php
index ef5583c93..441b7e537 100644
--- a/forms/TreeDropdownField.php
+++ b/forms/TreeDropdownField.php
@@ -203,12 +203,11 @@ class TreeDropdownField extends FormField {
 		$isSubTree = false;
 
 		$this->search = Convert::Raw2SQL($request->requestVar('search'));
-
 		$ID = (is_numeric($request->latestparam('ID'))) ? (int)$request->latestparam('ID') : (int)$request->requestVar('ID');
-		if($ID) {
+		$forceFullTree = $request->requestVar('forceFullTree')?$request->requestVar('forceFullTree'):false;
+		if($ID && !$forceFullTree) {
 			$obj       = DataObject::get_by_id($this->sourceObject, $ID);
 			$isSubTree = true;
-			
 			if(!$obj) {
 				throw new Exception (
 					"TreeDropdownField->tree(): the object #$ID of type $this->sourceObject could not be found"
@@ -240,7 +239,6 @@ class TreeDropdownField extends FormField {
 				$obj->markToExpose($this->objectForKey($value));
 			}
 		}
-
 		$eval = '"<li id=\"selector-' . $this->getName() . '-{$child->' . $this->keyField . '}\" data-id=\"$child->' . $this->keyField . '\" class=\"class-$child->class"' .
 				' . $child->markingClasses() . "\"><a rel=\"$child->ID\">" . $child->' . $this->labelField . ' . "</a>"';