Unfortuneately, as the parent of a U.S. Citizen, immigration regulations do not provide any special immigration benefits which would allow you to live in the U.S. with your children, until the children reach age 21 and can sponsor you for your residency. Your sister can file an immigration petition for you to immigrate, but it will take about 10 - 12 years in that category. You could explore obtaining an investment, work or study visa for yourself which would allow you to live in the U.S. while...