But if Heather has Alessa's memories, how could she not know exactly what happened?
See below about possible mental trauma.
Why would she imagine Harry's appearance incorrectly?
Artistic license on the part of the design team to make their characters distinct. I don't trust any of the characters' appearances in this game, knowing that any one of them could be just an incorrect recollection or a re-imagining. If she would remember anyone's face clearly it would obviously be her father, but hey people do forget the faces of the people they love most when enough time passes. It dosen't happen, but it's not impossible.
Except for Cheryl. Obviously based upon Heather, whose resemblance sparked this discussion.
How can the video tapes be real if they depict Dahlia and Harry being married and then divorced/involved in affairs/spousal abuse/alcohol abuse? (Harry's wife, a black haired woman instead of a blonde named Dahlia, died of illness and was a kind woman).
I assumed that the tapes were correct. I don't know for certain and neither does anyone else. What is know that is everything that we see is from the perspective of a mentally-unhinged Cheryl.
For all we know this is Heather, returning to another foggy world after trying to make sense of what happened to her father and her own past, and speaking to a phantom-shade of Kauffman who may or may not be leading her on about really exists. The video tapes could be part of it, even if they've always told the truth in previous games. Again, this is an assumption.
Of course, depending on what ending you get determines which video tapes you see. If the tapes are true, then obviously this theory is irreconcilable with the Sleeze and Siren ending, and probably the Divorce ending and the Weak Ending. Not so much the Drunk ending; still possible. Unlikely but not impossible.
Again, if these tapes are true (which we can never know for certain; it's taking place from Cheryl's perspective), then it is in fact a different continuity, but then all the different endings of every Silent Hill game are.
So, you're basically positing that Heather is so stupid she can't keep her own memories straight, creating entirely false delusions even though she's perfectly able to keep track of her three lifetimes during the actual events of SH3 while she's under monster attacks.
I posit nothing and I admitted as much many times. As I said before it is merely enjoyable imaginative exercise.
I cannot speak for Heather's intellect only of possible mental stability as Heather aged or went through a mid-life crisis or some other trauma from having such a disturbing childhood.
And even you or anyone else can claim to know exactly to what extent Heather remembers of her 3 life times worth of memories, only that she does remember being Alessa, and that was at being a teenager. Who knows what mid-crisis or other trauma drove her to possible confusion about those distant events? It would not surprise me if Heather later was in extreme denial about being Alessa or having connections with cults or their gods. It would not be the first time a Silent Hill character was confused about past events.
But then it's not exactly her memories are they? More like her own possible re-imagining of what her father went through based upon what fragments remain. Even if she remembered being Alessa or Cheryl, neither witnessed Harry's journey through Silent Hill. His notes? Him telling her?
After all both versions thought of their father as a brave man. It is a thin thread, I'll admit, but then I'm merely imagining here.
We know Cheryl's mother is named Dahlia Mason; it's not up to debate. Moreover, even if she WASN'T, she appears to pick up Cheryl from the clinic in the ending. Who the fuck is she, if not her mother?
Admittedly I did not get that ending on my recent playthrough, however, if I were speculating about possibilities as to the identity of the woman who picked up her up at the clinic, I would say: a shade of the villainous Dahila Gillipse, still existing in some form? Another manifestation of this false scenario as Cheryl finds comfort in the arms of a false mother, even one named after her cruel actual mother? A hallucination? Did Kauffman see her? Perhaps this is a repeat of Harry's scene at the bar with Michelle, only Heather believes that the person that is picking her up at the clinic is her mother? As others have posited before: could Harry Mason have re-married at any point? Unlikely, but not impossible.
Again, just speculating. You're probably absolutely correct. After all Kauffman did say "Your mother is alive and not the monster you make her out to be." Still, I don't trust any version of Kauffman, real, alternative universe, or possible ghostly manifestation.
2010. SH3 takes place in 1997, by the way. SH3's Heather, then, would be 30.
If you don't mind, I would like citation of this. It's not that I doubt your word, only that it would clarify things.
I bring up this speculation because the thought of the producer Tomm Hulett first outright saying that it was taking place in a different continuity which I will accept gladly if that is what the maker of the game says...
...but what intrigues me is that he retracted that statement, saying that it taking place in a different continuity may not be true.