[solved] addOne vs. save(), toPlaceholders naming

$parent->addOne($child,"ChildAlias");
vs.
$child.save();

/* create user and profile */
$user = $modx->newObject('memberUser');
$user->fromArray($fields);

$profile = $modx->newObject('modUserProfile');
$profile->fromArray($fields);

// must save user first to get back id, otherwise internalKey can not be set later.
if (!$user->save()) {
    return $modx->lexicon('register.user_err_save');
}

$profile->set('internalKey',$user->get('id'));
//$profile->save();  //   <--  this one CAN be bypassed, as later on there's a $user->save()
$user->addOne($profile,'Profile');   // <----    better then save()

....
.... all the rest of my custom addOne/addMany related to extended $user
....
// everything was ok?    let's commit to database
$user->save();   /* final user save to update relationships */

print_r($modx->placeholders);

$modx->toPlaceholders($memberUser->MemberLinks,'MemberLinks');

[MemberLinks.55.title] .... [MemberLinks.56.title]

/*  same as toPlaceholders, but naming in 1.2.3.4.. order, and not PK-based (as toPlaceholderS)  */
function chronologicalPlaceholder($parentObj,$alias,$prefix) {
	global $modx;
	if (!isset($prefix)) {$prefix = $alias;}	// default to use alias as placeholder prefix
	$childs = $parentObj->getMany($alias);	// get all children
	sort($childs);			//change array's keys  to 0,1,2,etc...
	array_unshift($childs,array());   	// add empty one, simply so the numbering will start from 1 and not 0
	$modx->toPlaceholders($childs,$prefix,".");	// generate modx placeholders for templates
	return $childs;	// return the array, needed for recursive placeholder (grandchildren relationship or more)
}

/* add your schema */
$model_path = $modx->getOption('core_path', $properties, MODX_CORE_PATH).'components/yourName/model/';
$modx->addPackage('yourSchemaName',$model_path);

$memberSchemaDef = '{"Profile":{},"MemberLinks":{}}';
// and so on.... add all your salat here...   note:  doesn't support grandchildren or deeper (although looks like it should, by design...)


/* get extended user object */
$memberUser = $modx->getObjectGraph('memberUser', $memberSchemaDef , $userId);
if (!isset($memberUser)) {return;}   // if empty?  quit.

$modx->toPlaceholders($memberUser->Profile,'Profile');   // simple example, "profile" has 'one' relationship with modUser
chronologicalPlaceholder($memberUser,"MemberResidencies");   // has 'many' relationship with modUser (well actually to "memberUser" object that extends "modUser"

$skGroups = chronologicalPlaceholder($memberUser,"MemberSkillGroups");   
foreach ($skGroups as $i => $skGroup) {
	if (count($skGroup) > 0) {    // has any professions?
		chronologicalPlaceholder($skGroup,"Professions","MemberSkillGroups.".$i.".Profession"); 
	}
}