I would invoke the Nick Bate doctrine. Formed after it was proven Nick Bate raped his younger sister and mader her eat his shit after 'joking' for years about raping her and 'joking' about being into scat.
Nick jokes about child rape a lot, often its framed as Catholic priests being pedos but he also jokes about himself raping a child and his children being raped.
Nick is speculated to be a sociopath if not an outright psychopath, this is most evident that he can never admit he fucked up and made a mistake. Even when his kids are taken away because he wasn't feeding them or washing their clothes and lots of coke was found in his bedroom, its the government out to get him. He has tried to get his kids back and seems to be glad they're gone.
Nick murdered a whole family of racoons because they dared to forage for food around his place, shooting them from a tree when they were clearly down with his house and moving on. He has also said he likes to drown racoons and other small animals (no blood to clean up).
His daughter who had tested positive for ingestinng cocaine, was the same daughter he has said numerous times was his favourite and that no one but him and Kayla really get her. She has also displayed symptoms of child sex abuse with her having constant nightmares, agression towards her parents (saying she'd murder them) bedwetting and refusing to clean herself. This last point I'd like to note is that she was one of the kids that stayed home all the time and didn't go to school (go to someone else house for homeschooling) to hide the neglect. She got the dirtiest the quickest despite her clearly getting favoured attention being the favourite child and getting cocaine in her system. Refusing to clean yourself so your abuser will leave you alone from being repulsed is a very common tactic for children and teens to avoid further abuse.
Nick had the weird idea from American beauty that the main character should have molested his daughters best friend because she was a virgin.
Cocaine and drinking heavily every single day has clearly made him far more loose with his actions regarding sex.
Nick lied about everything we now know is true regarding his swinging, drug use etc. It always got worse the more we learnt as well
Nick is friends with pedos/pedo supporters
1. Has no qualms violently killing peaceful animals, enjoyed shooting and drowining them
2. No empathy or regret for his actions
3. Favourite child (his daughter who is not the youngest, oldest or the only daughter, so no 'normal' reasons to be the favourite) was his only child to test positive for cocaine consumption
4. Much looser sexually willing to do and try anything for a new experince
5. Has joked about child rape, and his own children being raped repeatedly and gone out of his way to make said jokes
All this and the Nick Bate doctrine has convinced me Nick raped his daughter. I'll admit I was wrong if there's any proof he didn't, or simply no further proof that he did is found. But all this circumstantial evidence has convinced me he did. A man who has the behaviour of killing small defenceless animals, no regret when he implodes his own life via drug use, walks away from a moving thinking not raping a teenage girl as a mistake because shes a virgin and he 'deserved it', is entirely capable of raping his own child.