Like JT Leroy? (Who, as some people will remember, was a reclusive US author hugely in vogue in the 90s, who wrote semi-autobiographical novels about his supposedly poor, abusive past as the son of a truckstop prostitute, and who turned out to be the fictional creation of a woman called Laura Albert, whose sister in law ‘played’ JT Leroy in interviews in a wig and dark glasses after a decade in which no one had ever seen the supposedly pathologically shy author in the flesh. Until journalists started poking around and pointing out factual discrepancies, and no one in the bit of LA where JT Leroy claimed to have been a teenage prostitute and heroin addict had any memory of him.)
Actually, from what I remember, LA ended up in a fraud case for having signed a movie option deal using her pseudonym, and she lost.
Perhaps ‘Sally and Tim Walker’ is a double fictional persona (invented by Dave and Julie, or SA, or ‘Polly’, or the Walker children, or the brother with the chateau.) And the woman we see on the Insta feed, doing press, performing with Gigspanner etc is an out of work actor. Likewise Tim-Moth, who was picked up by someone who heard him telling tall tales on a building site. 😀