Based on a question I asked myself while watching the movie: Why the heck is Tina seeing Credence in her execution memories? Since they were seemingly supposed to be about her dead parents or at least happy memories.
Memorabilia
Porpentina Goldstein has always been a pureblood witch, just like every other witch in America. Muggleborns, as they are called in Britain, do not exist and never have, because Magicals have never bred with No-Majs. The MACUSA is of the firm believe that every "Muggleborn" found in other countries is actually a descendant of a Pureblood and nothing else. A squib has lost the magic found in his family and therefore all his descendants will be without magic.
Tina knows all this. It has been taught since she was a young girl. It is also one reason why Magicals are never to interfere with No-Majs. One wrong interaction and the Muggleborns could lead to the discovery of magic. After all they would live in non-magical environments while having a volatile magical core just waiting to use accidental magic.
But there is no reason to worry really, because no Magical in America would ever have any sort of relation with a No-Maj. Therefore there does not have to be any sort of watch over the No-Maj World for those kinds of children.
Tina doesn't have to worry about any of this either way. She is still only a child, no matter how much good she wants to do. In a few months she will go to Ilvermorny, the magical school of America and she can't wait. But first she will have to go through the yearly inspection.
Every year for as long as she could remember her family is inspected by the MACUSA. It is a standard in America, because children are important and to be well loved. The MACUSA wants to ensure every child grows up well. There have never been any problems in her inspections. She is well loved.
She doesn't like how the one Inspector needs to look into her head though. It feels icky and afterwards she always has a little bit of a headache. But she's a big girl! It is only a little...
Even if she feels like little ants inside her head are dragging away, eating away, maybe just hiding away tiny bits of herself, she is fine! It was probably unimportant anyway. MACUSA takes care of her and would never do anything bad anyway, so it is just unimportant.
Queenie is her little sister. She can see into her head too, but Tina never feels it. She doesn't know if that's better or worse. But either way, Tina will always protect her little sibling. That's what siblings are there for, to protect each other!
That is one thing Tina will never forget.
Sometimes Tina is afraid of her mother. She doesn't know why; her mother is the most loving and gentle person she knows. She likes to hug the sisters and tug them in at night, even if they are getting a little old for that. But at some point Tina realises she isn't just afraid of her mother, but of just about every adult woman. She doesn't understand why and learns to ignore her fear.
Queenie loves to play dress up together. They wear different clothes: dresses, skirts and whatever else Queenie can get her hands on. Sometimes she even steals from their mother's wardrobe. But Queenie never uses belts. Because the one time she wanted to use one so father's pants (because mother would never wear pants. They are only for men!) would sit right on Tina, Tina flinched away and screamed out loud, instantly crouching into a ball.
Tina never again sees belts in the household.
Credence is Mary Lou's oldest child. He has grown up with her all alone until Chastity came a few years later. He always does his best to protect his little sister, later sisters from their mother, but often wishes there was someone else to protect him as well. Chastity and Modesty have never protected him, only looked at him with worry and pity they, while he willingly took blame for many of their mistakes. He sometimes almost remembers someone doing the same for him.
His back, his arms, everything hurts him. His skin is always wounded, scars litter every part of his body. No one helps him.
Once every few years maybe an inspector will come to make sure the church they run goes well. He only talks with Mary Lou and listens to her tell all about witches and evil and Satan. He never acknowledges the fear in children's eyes, their flinching forms or the blood encrusting the boy's clothes. The scars on Credence's hands do not exist.
When the Inspector goes he wishes the family luck. No one else comes to take them away.
Before Modesty came, her room was empty. In the empty room stood a bed, and Credence would often go there and lie down on the bed, imagining someone hugging him and telling him they would leave as soon as possible. They would run away, they would protect each other. But as soon as Credence left the bed his fear would come back and he couldn't run away, couldn't protect himself. He couldn't do this alone.
Once Modesty occupied the room and bed he couldn't seek comfort there anymore. He slowly forgot there was any to be had.
One day he realises he is technically an adult now. He could leave any time now. But he doesn't know how to do that. He doesn't know a different life and he can't do it alone. Either way, he can't leave his sisters.
So he stays, feeling himself fraying and splinting, slowly something inside of him seeping out. It feels black and horrifying, so he makes sure to 'put a lid' on it.
The young man can almost remember a time when he was young and used strange powers. A time when he could control himself and a strange, wondrous power he and someone else secretly called magic. He almost remembers a strong sister who protected him.
But in the end all those are only impressions, like ashes in the wind. He can see the dust, but it is gone as easily as it was there. Whenever he feels the black creeping out, he almost remembers and he can contain it.
One day, while Mary Lou once again has him and his sisters give out the pamphlets as she speaks to the masses, he meets a young woman with brown hair and a surety in her step he envies. He also subconsciously relaxes when she speaks to him, asking about his mother and her work.
He only realises his folly once Mary Lou comes from behind him, flinching and almost losing the pamphlets. The look his mother gives him makes him certain he will be punished. He curls his shoulders together as much as he can while still standing.
He hears the woman talk to his mother and when he glances up, looks into the woman's eyes. Credence sees Tina's eyes widen, feels his own heart almost too loudly as he remembers a girl being beaten by a belt and more senses than sees the young woman who had been his sister take his arm and pull him behind her as she takes out a wand and a bright light hits mother.
Tina breathes heavily, when suddenly a mass of people in strange clothing appear and throw light all around. He blacks out, hit by a light.
When he wakes up he is in his room, on his bed, and mother comes in to demand his belt.
A man in a coat walks through MACUSA. He has just come back from putting another No-Maj-born into a loving magical family. No one will remember anyone but another pureblooded child. Time to create the appropriate files.
The idea is that Tina is actually a muggleborn and was another adopted sister of Credence. She protected him as best she could until she was taken by the MACUSA. The MACUSA itself doesn't want to interact with No-Majs at all, as is known, but that would make no sense with muggleborns existing. So in this story, they take the muggleborn from wherever they live, obliviate everyone, place the muggleborn into an adoptive family and change everyone's memories. For that to happen they have a secret department that does all this and regularly checks on the magical family, but doesn't really care about the No-Majs. Tina remembered Credence during the execution because he was her brother and meeting him again was kind of happy. The memories shown during the execution were supposed to be happy memories about family. Of course everyone was obliviated of the incident. Tina later on by the special department. Memorabilia pretty much means "something memorable". It is this story's title because even after being obliviated, Credence and Tina still know something isn't quite right and little things of their past still shine through.