NSW Can overstay of U.S Visa for 10 months affect student visa for Australia as a defacto partner?

[al joulson]

I have a U.S visa and I overstayed 4 years ago back in 2014 for 10 months and I am back in my country of origin. My partner is applying for a student visa and I am going as a defacto partner with her to Australia. Should I mention this information and if I do, is it grounds for denial of the student visa? Or should I not mention this information because it was 4 years ago and I never returned to the U.S. I am concerned whether I should maybe not mention this because it'll be bad for the Australian student visa. What are my options please?