Yes I understand I do need to file taxes, just for various circumstances over the past 2 years it's been very challenging. I intend to file and get everything caught up after we return to the US. We shouldn't owe anything but I understand it still needs to be done.
To clarify, I am a US citizen, and I would be petitioning for my adopted children. According to what I've read, due to Child Citizenship Act they will be admitted as LPR/green card but immediately change to citizens, therefore the I-864 and financial sponsor not needed. On the I-864 form instructions, it says:
Are There Exceptions to Who Needs to Submit Form I-864? The following types of intending immigrants do not need to file Form I-864:
2. A child who will automatically acquire U.S. citizenship under INA section 320, as amended, upon being admitted to the United States. Children become U.S. citizens upon admission to the United States as a lawful permanent resident (LPR) or adjustment of status to an LPR if they are under 18 years of age, unmarried, and residing in the United States in the legal and physical custody of their U.S. citizen parent. They also need to meet the definition of child at INA 101(c) which is applicable to citizenship. (For more information on definition of child, see USCIS Policy Manual, Volume 12, Part H, Chapter 2, Definition of Child for Citizenship and Naturalization at https://www.uscis.gov/ policy-manual/volume-12-part-h-chapter-2). Adopted children need to meet the requirements applicable to adopted children, including having a final adoption (See uscis.gov/adoptions)
I just recently learned about that exception so I hope my understanding is correct because that's very exciting!