That is a tough one. Without a court order granting sole custody, it will be hard. You might have to hire a lawyer there and to speed it up, you may have to have him/her bribe someone in the courts. The big problem is that US embassy will not approve without a signed waiver, court order or certificate of death. Since he won't sign, the only way is through a court order. If he has not been paying any child support on a regular basis, it will be fairly easy to get court order but still would take time. You could ask for extension on K1 if it has already reached embassy. Request 6 month extension for interview. They generally have no problem with that, but if you do, remember you will have to get police certificate again, send updated tax returns and bank statements, which should not be too difficult. Other than that i do not know of any other way around. In general I would think there is something the ex wants, even though he says otherwise. Hopefully it isn't something ridiculous like a new car, but these men over there no the laws. I wish you success.