I think all you can do is be direct about how unhappy it's making you. If she's not a great one for social media, she may not want to join in a family WhatsApp group. It's a shame for the children - my grandchildren and great nieces and nephews met up at a family event , and got on really well - two smallest were walking hand in hand and calling each other friends by the end! Things could change - just keep the lines of communication with the family open - stents are very good for that!
He has done it! The toolmakers son has resigned!
