Hmmm... If the parents had ever asked her not to come to school events, for whatever reason, or not to come unless they invite her, that may be why they were angry at her going o the rehearsal. In fact, if attending school events has been an issue between them, that may be why they didn't believe her. However, there does seem to be more going on there than just that.
Lindadrew, I'm so sorry your planned visit was canceled and that you have dealt w/ the drama of family problems both as a child and a GP. Do you really think your parents were "snakes" though? What reasons did they give you, if any, for cutting off so much family? You must have missed them terribly and again, I'm so sorry.
As for your GC, it sounds as if DS is trying. Perhaps he should talk it over w/ XDIL before he gives you an answer in the future though? Then you won't get all prepared, just to be disappointed. Does he have visitation? Perhaps he can bring your GC to see you on his time, now and then? In that case, I don't think XDIL will be able to prevent it.