gistfile1.php

<?php

class OurPeoplePage extends Page {

	private static $many_many = array(
		'Team' => 'TeamMember'
	);

	private static $many_many_extraFields=array(
		'Team'=>array(
			'SortOrder'=>'Int'
		)
	);

	public function getCMSFields() {

		$fields = parent::getCMSFields();

		$config = new GridFieldConfig_RelationEditor();
		$config->addComponent(new GridFieldSortableRows('SortOrder'));
		$config->addComponent($uploader = new GridFieldBulkUpload());
		$uploader->setUfSetup('setFolderName', 'TeamMembers');
		$config->addComponent(new GridFieldBulkManager());
		$config->addComponent(new GridFieldGalleryTheme('Image'));
		$config->getComponentByType('GridFieldAddExistingAutocompleter')
		       ->setSearchFields(array('Title', 'Position', 'Email'))
		       ->setResultsFormat('$Title');
		$fields->addFieldToTab('Root.TeamMembers', new GridField('Team Members', null, $this->Team(), $config));

		return $fields;
	}

	public function Team() {
		return $this->getManyManyComponents('Team')->sort('SortOrder');
	}
}

<?php


class TeamMember extends DataObject {

	private static $belongs_many_many = [
		'OurPeoplePages' => 'OurPeoplePage',
		'ContactPages' => 'ContactPage',
	];
}