Mothers court witness not proven in real life

When I went through a second custody "battle" in the Family Law Courts, the mother stated, under oath, "They are old enough to make the decision. I would never want them to live with me if they don't want to. If they choose you, I would be very upset but I will continue to love them and try to be the best parent I can.". Then; the judge gave her custody and let her move to Singapore with her boyfriend, who happens to be closer to my daughters age than hers.. Now my daughter is 16 1/2 years old and wants to come live with me (in HK currently). In fact, she is desperate to come live with me. She has had troubles with her mother, which led to minor incidents (she is a teenager). All she wants is a fresh start away from all these troubles so she can finish her last year of education. But, her mther will not let her. My daughter was so adamant she refused to go to school for the first days of term. How do you go about keeping her mother to her words, under a sworn oath to the family law court. Its perjury in a backward form.