:tyou: Nursie!
I think since Dad has an attorney who stated Dad worked to block a removal of the kids from the state it's probably likely both children are entered into the CPIAP list.
Theoretically when a parent is leaving the country (or even a certain mileage outside court jurisdiction depending on state law) the primary parent should have custodial agreements with them. CBSA is supposed to question parents whom are entering Canada with children but I have a sneaking suspicion it probably isn't well monitored. JMO
Russia doesn't entertain the visa waiver program though so it is my understanding that Mom and any children traveling with her would need both valid passports and visas just to enter Russia. In order to be granted visas she would have had to make application to the Russian Embassy and they would have checked her custodial status.