Access all properties of related products

Hi,
I'm new to Lightspeed and I'm trying to modify an existing theme.
I'd like to access some extra properties om related product in the product detail page
For example relatedProduct.stock.available, but it's always false.
{% for relatedProduct in product.related %}
{% endfor %}
Same thing in the cart popup, you have the product in there but product.data_01 is always null.
Am I missing something here ?
Regards
Sven Peeters