Franz, she wasn't sitting on her like you think, her other leg was holding her weight . Nube wasn't getting squashed, she is used to Natalie being all over her. Nube wasn't complaining at all, she loves the attention she gets off Natalie, really.
besides, I think this photo shows what a great character Nube has, loving and carefree with kids,it shows what a spectacular breed they are with children, any other dog might not have the same pacience and bite, but the mastins are so docil, and super loving, thats what I love about this breed being a mum.