Rashi on Genesis
חתניו SONS- IN-LAW — he had two married daughters in the city (Genesis Rabbah 50:9).
Radak on Genesis
ויצא לוט ...לקחי בנותיו, they had become the sons-in-law having already betrothed his daughters to them. The Torah does not report that Lot spoke to his daughters, as it was understood that the daughters would concur with their husbands’ decision.