DP has already been asked by his ex to vary (significantly) the contact arrangements in place for the summer holidays this year. Her proposal reduces length of the blocks of time DSS spends with us, but doesn't reduce the overall number of days iyswim.
If DP refuses, then we know that DSS will spend days at a time in the sole care of his grandmother, for whom he is being given increasing caring responsibilities when he is with her.
It seems like the court order is worthless after all 