Вставить один simplexmlelement в другой

simplexml_ex.php

<?php 

class SimpleXMLElementEx extends SimpleXMLElement{
  public function appendXML(\SimpleXMLElement $data): void
	{
		$name       = $data->getName();
		$nameSpaces = $data->getNamespaces(false);

		$qualifiedName = $name;
		$value         = null;
		$namespace     = "";

		if (!empty($nameSpaces))
		{
			$prefix = array_key_first($nameSpaces);
			if (is_string($prefix))
			{
				$qualifiedName = $prefix . ':' . $name;
				$namespace     = $nameSpaces[$prefix];
			}
			else
			{
				$namespace = $nameSpaces[0];
			}
		}

		if (strlen(trim((string) $data)) == 0)
		{
			$xml = $this->addChild($qualifiedName, null, $namespace);
			foreach ($data->children($namespace) as $child)
			{
				$xml->appendXML($child);
			}
		}
		else
		{
			$xml = $this->addChild($qualifiedName, (string) $data, $namespace);
		}

		if (!empty($nameSpaces))
		{
			foreach ($nameSpaces as $p => $ns)
			{
				foreach ($data->attributes($ns) as $n => $v)
				{
					if (is_string($p))
					{
						$xml->addAttribute($p . ':' . $n, $v, $ns);
					}
					else
					{
						$xml->addAttribute($n, $v, $ns);
					}

				}
			}
		}
		else
		{
			foreach ($data->attributes() as $n => $v)
			{
				$xml->addAttribute($n, $v);
			}
		}
	}
}