Ahhh- that is a great immigration question and there are many outstanding IMM attnys here always contributing to avvo, repost under immigration and I am sure you will get a bunch of great answers today. If you children live in the US and you are a US Citizen it does sound like you have options.
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They might already be US citizens, depending on how long you lived in the United States. If so, it is only a matter of filing for Certificates of Citizenship and/or U.S. Passports. If not, you can petition for them to become lawful permanent residents, after which they can become U.S. citizens. Please consult with an attorney experienced in U.S. immigration law who can figure out whether they are U.S. citizens already.
This answer provides general information only. Please see an experienced immigration attorney for a complete answer. 203 645 6376.