I really wanted to know if the twins got a little sister, why the ML has his issue/ can he ever get close to his mom again, if her brother had kids, if her main maid ever got preggo, and if the original ML became happy

she was living in a zombie apocalypse and it was never stated how old she was when zday happened. For all we know she could have just been a child when the zombies came about. She does say she survived for a while, watching all her friends and family die before the zombie king was killed. I have a feeling zombie land was probably more primative than ancient China, so she would have been used to worse. Also, she doesn't transmigrate into the book, she is reborn into it. For the first 16 years she lives as a normal ancient Chinese girl until the flood of memories from her past life and the book come to her. So it makes sense that she would still be okay with the age gap.

I get that she saved the MC's father from becoming a s*ave or even being put to death, but I feel like the slate should have been wiped clean when her son tried to mu*der them and all the crap the aunt pulled.

Also I think another reviewer had it wrong, the MC's father was the grandma's sister's son. He had no blood relation to the grandfather, just the grandma. The grandma really did do a good thing by sheltering him and put her and her family at risk by doing so. It also said that though she favored her son more she treated him well until he ignored her wishes and married the MC's mom. Then she becomes jealous at his success and his kids success to the point there are no feelings left. So the MC in exchange for her sheltering the dad will shelter that branch. As the dad explained it, he felt guilty because if he wasn't sheltered than main branch wouldn't have tried to kill him and wouldn't had their title revoked.

She's a transmigrator from zombie apocalyptic world and knows she's transmigrated to a rebirth revenge novel, so she knows every future event, like the originalFL.

She has a mysterious ability and can make various magical wines that can cure anything

The NFL recognized that it was purely her interactions with her 5th sister that was ultimately going to lead to the unhappiness of said sister. She distances herself away from the sister not to abandon her, but to make she that the sister doesn’t develop feelings of pity and an urge to seek vengeance for the NFL (which will lead to the sisters downfall). The NFL warns the sister not to hit the bottom line of her fiancé and actually praises him to help the sister develop good feelings towards him. Keep in mind, if the NFL intervened and prevented the sister from getting engage to the fiancé (which she knew for a fact was not actually a bad guy and was pretty decent), it’s unknown whether the sister would be then forced to marry someone who is actually horrible. Additionally, marriages are decided by the parents in this time period and respecting ones elders is valued highly. The fiancé isn’t bad, it’s what the sisters (she’s really the cousin of the NFL btw, just called 5th sister) parents want, and the future is less uncertain. If anything, the NFL is helping the sister out. Just not in a totally active and direct way. The NFL even notes that it was the compassion of her sister towards the NFL that led to her sisters downfall in the past. Therefore, the NFL tries to diminish said compassion.

the FL reincarnated from a post zombie-apocalypse world in which she had the ability to brew medicinal wines that could cure basically anything she wants.

married Prince Jin as a concubine and helped him get the throne but then was pretty much destroyed in the harem and died a painful death.

doesn't really do anything bad other than the original breaking of the engagement at the beginning of the story.