Legally the child support goes to the person in care of the children. And I believe if the caregivers are not fit responsible you would get full custody of them. I would definitely check into this with FOC immediately.
Question 1. Why were you not informed at time of move? 2. Who has them? 3. Why were you not asked to take custody? 4. Unaware for 1 year, come on you fell down on the parenting job. You can ask for proof that the caregiver is being given the child support. Depending on how the separation and child support were worked out either get a lawyer or go to the court who issued the child support decree for information.