How to Get Grouped Product by Associated Product

If simple products are under Group1 category try following code to associate them to grouped product of this category:

    $productCollection = Mage::getResourceModel('catalog/product_collection')
        ->addCategoryFilter($category);
    $relation_data     = array(); //Grouped - child relation data
    $groupedProduct    = false; //Grouped product
    foreach ($productCollection as $product) {
        if ($product->getTypeId() == Mage_Catalog_Model_Product_Type::TYPE_GROUPED) {
            $groupedProduct = $product;
        } else if ($product->getTypeId() == Mage_Catalog_Model_Product_Type::TYPE_SIMPLE) {
            $relation_data[$product->getId()] = array(
                'qty'      => 1,
                'position' => 0,
                'ids'      => $product->getId()
            );
        }
    }
    if ($groupedProduct) {
        $groupedProduct->setGroupedLinkData($relation_data);
        try {
            $groupedProduct->save();
        } catch (Exception $ex) {
            Mage::logException($ex);
        }
    }

I solved this way getting the price of the last product associated (the prices of my products associated are the same for each product so I need to check what is the lowest):

<meta property="og:price:amount" content="<?php 

$product = Mage::getModel('catalog/product');
$product->load(Mage::registry('current_product')->getId());
$grouped_product_model = Mage::getModel('catalog/product_type_grouped');
$groupedParentId = $grouped_product_model->getParentIdsByChild($product->getId());
$_associatedProducts = $product->getTypeInstance(true)->getAssociatedProducts($product);

foreach($_associatedProducts as $_associatedProduct) {
    if($ogPrice = $_associatedProduct->getPrice()) {
        $ogPrice = $_associatedProduct->getPrice();
    }
}

$ogPrice = number_format((float)$ogPrice, 2, '.', '');
echo $ogPrice . " Euro";

?>" />