I just found this post on Tumblr which makes a good point and made me laugh
'They don’t want their children to have a relationship with Harry’s family, they want them to have a connection with The British Royal Family, which is why we get all the demands, phantom invites, and threats. JH’s complete incomprehension as to why his family were so ‘frosty’ makes me think that despite having the greatest social and educational advantages in the world Harry’s intelligence level is on par with being watered twice a week.'