Can a 20 year old help their parent become a citizen?

How can I, as a U.S. citizen, apply for residency for my mom? I am currently 20 years old and my mom came legally to the US and she overstayed. I know the law says I have to be 21 in order to file a petition but what if i can get an affidavit? or can I do something else now so that my mom can adjust her status? My uncle also filed an I-130 petition for her five years ago but unfortunately my uncle passed away before a decision was made, so then my other uncle filed another petition for her two years ago (they are both US citizens) Can we do something so that USCIS count both applications as one when the first application was filed? Can she adjust her status? Any process (either by me or my uncle) will help in order to get her a work permit or something.