Midrasch zu Dewarim 22:21

15) I might think that the penalty was burning even if she were single when she fornicated; it is, therefore, written here "her father," and there (Devarim 22:21, in respect to a betrothed maiden) "her father. Just as there, the reference is to fornication within the context of marital ties, so, here. — But perhaps the thrust of "her father (a Cohein)" is to exclude (from burning a maiden [even a single maiden] who fornicated with her father) — with any man (i.e., with her father who is not a Cohein)! — (This cannot be, for) "she profanes (her father)" implies (that her fornication is with) "any man." (For if it were with her father, then he would be profaning her). How, then, am I to understand "her father"? As "Just as there, the reference is to fornication within the context of marital ties, so, here."

(Devarim 22:21) "and the men of her city shall stone her": Now do all the men of her city stone her? (The intent is that she shall be stoned) in the presence of all the men of her city.