Rights of non custodial parent in a divorce wherein death occurred to custodial parent
Non custodial non US citizen parent (father) lives in Mexico. Custodial parent of two minor children (5 years old and 1 year old) is US citizen in Illinois. Divorce papers named father but set forth no requirements or terms for visitation, child support etc. There has been little if any contact between children, custodial parent and non custodial parent. Custodial parent lives with her mother and between them, they take good care of minors.
Question(s). IF something were to happen to custodial parent (death, incapacitation etc) can the non custodial parent assert his rights to children and take them? Is it likely the State would step in? Is there anything that can be done now to ensure that if something untoward were to happen to custodial parent, the non custodial parent would be barred from stepping in and the care of minors would revert to custodial parents mother?
Any help or direction is appreciated.