My 6 yr old DS is great friends with a group of 4 boys who often visit each other's houses after school. The mother of 2 of them, twins, repeatedly leaves my DS out and invite the other boys round but not him. I've had the twins at my house to play but it takes the mother about 6 months to invite DS back. In the meantime she is inviting the other friends round constantly and I have to deal with DS upset and tears each time he is left out. These twins are really good friends with DS in school and they keep telling him that he is coming to their house which makes it even harder when he is not invited.
I am fed up with my DS being so upset and left out all the time. How should I deal with it? I think I will encourage friendships with other boys so that DS doesn't feel so reliant on these twins.