if she’s married to a US citizen then she isn’t undocumented
Untrue. It depends on how long you were out of status and what sort of status you had in the first place. If you never had a visa in the first place you really are shit out of luck and can only apply for a green card after you self deport (which may get you a 10 year ban on reentry after you so it or if you've entered the country illegally more than once you get a lifetime ban with no possibility of appeal even if you're married to an American citizen and have American citizen children with them).
https://www.boundless.com/faqs/overstayed-visa-marriage-consequences/
https://www.uscis.gov/sites/default/files/document/guides/A2en.pdf
Brother, we sell them in every 7/11 in the US and we pack them with cheese. They are mass produced turds.