Adam Clarke on Genesis 19:12

Hast thou here any besides? son-in-law - Here there appears to be but one meant, as the word חתן chathan is in the singular number; but in Gen 19:14 the word is plural, חתיו chathanaiv, his sons-in-law. There were only two in number; as we do not hear that Lot had more than two daughters: and these seem not to have been actually married to those daughters, but only betrothed, as is evident from what Lot says, Gen 19:8; for they had not known man, but were the spouses elect of those who are here called his sons-in-law. But though these might be reputed as a part of Lot's family, and entitled on this account to God's protection, yet it is sufficiently plain that they did not escape the perdition of these wicked men; and the reason is given, Gen 19:14, they received the solemn warning as a ridiculous tale, the creature of Lot's invention, or the offspring of his fear. Therefore they made no provision for their escape, and doubtless perished, notwithstanding the sincerely offered grace, in the perdition that fell on this ungodly city.