In light of this quarantine, I am spending shabbat at my non-observant family's and the house is not kosher. I have my own pan where I cook all of my food but I recently ran out of paper plates (still have utensils, cups). I was wondering If I could possibly eat from a glass plate that had non-kosher food on it at one point in the past as long as I thoroughly wash it so there are no visible stains (which is permissible unless I am mistaken according to Sephardic authorities).

In light of this quarantine, If someone is spending shabbat at non-observant relatives and the house is not kosher. If the person runs out of paper plates, would he be able to eat from a glass plate that had had non-kosher food on it at one point in the past as long as it was thoroughly washed so there are no visible stains (which is permissible unless I am mistaken according to Sephardic authorities).

Note that this assumes that the person was unable to run to the store to buy new paper plates.