Additionally to that about the theory with the missing Marjorie:
Folklore woman is mainly held in black & white because she is dead and "seven" is told from Marjorie's POV:
being mourned aka dead so the missing one
wandering in the trees as ghost, maybe sitting in them as in seven -> "please picture me in the trees"
A place where the sister might always had a great time together, just the two of them
the story about her disappearing passed down like a folklore at one point ->"passed down like folk songs"
wearing a night gown, very untidied hair, in a way like you wouldn't go out this way in the woods, but she does since she is a ghost
also the mad dad would fit so well to a father's feelings after a child dies/goes missing and a situation like this will permanently haunt a family -> "I think your house is haunted" It is no longer her home. She is living the forrest as a ghost where she was always doing great with her sister.
She is "high in the sky with Pennsylvania under (her)" as in heaven after she died
You know how people say memory can fade away? -> "and though I can't recall your face"
But a sister's love will "last(s) so long" even when they aren't physically together
also Marjorie has the dire need to tell her that, no matter what happened, they're still sister and she is there for her, even if it's not physically and maybe even going back to play games together -> "And we can be pirates. Then you won't have to cry"
And very importantly Marjorie tells her she doesn't " have to cry or hide in the closet" when her parents, especially her father might be so extremely mad and sad that Dorothea lost her younger sister Marjorie
Marjorie also sings in "seven" these very important lines showcasing what a child is behaving like when playing (in the forrest) and what she never got to learn because she never could grow up. When doing this she also asks her older sister to also never forget her when she was young -> "Please, picture me in the weeds before I learned civility. I used to scream ferociously. Any time I wanted"
It also strikes me about how the missing Marjorie might reminisce about the summers and drinking sweet tea while making up little plays and dreaming about places together, sitting in the trees and giving unbreakable promises. The siblings give to each other. Asking Dorothea to never let go of the memory -> "Sweet tea in the summer. Cross your heart, won't tell no other. And though I can't recall your face. I still got love for you. Pack your dolls and a sweater. We'll move to India forever. Passed down like folk songs. The love lasts so long"
evermore woman is mainly in colour because:
it is Dorothea, the sister alive who lost her out of sight while presumably playing hide-and-seek
braided hair as observed by her missing sister (your braids like a pattern)
looking for her sister in the forrests or simply going back to the memories she had. You might so should be aware that is is said, if something like ghosts and spirits exist, children are most likely to be the ones who can see them ( hence imaginary friends) so what if Dorothea goes back to the forrests where she so often found her sister's ghost and where they might have played hide-and-seek?
Her attire looks more like someone who would go for a walk in the forrest, also like an adult
And if I might not be totally going crazy I want to add another point to think about:
What if Taylor's parents told her as the big sister the story when she was a kid and they lived in Pennsylvania? As a reminder to always look out for your younger sibling. It was passed onto her almost like a .... folklore?
Can't wait to analyse more about this tomorrow.