Kill Me More Times, I'll Become Invincible - Chapter 15:

To care for her ailing sweetheart, college student Lu Chenchen gave up her white-collar office job and chose the higher-paying caretaker profession instead. Going around in circles, she ended up at the Mao family’s home.

The Mao family background was complicated. Old Madam Mao was not her son Yanning’s birth mom, but his young aunt. His wife was Old Madam Mao’s first love’s daughter, spoiled and pampered. Despite over ten years of marriage, husband and wife were distant.

To repay Old Madam Mao’s kindness in raising him, and for the sake of his three children, Mao Yanning endured again and again – not just a loveless but outright destructive marriage.

Lu Chenchen walked on eggshells among these people – carefully serving young and old, currying favor with the lady of the house without offending the man of the house, while also worrying about his sweetheart’s illness and missing “his” elders and children back home. Her heart was like a cookie flattened between the pages of life, living a difficult and cautious existence.

However, as the saying goes, “You reap what you sow.” A life that has been polished will eventually shine with a brilliance that ordinary years cannot compare.

Su Ran, a music prodigy, woke up transmigrated into a book.

At that point in time, the main story arc in the book had already been completed. As a villainess female supporting character, not only did she need to take over the original owner’s pitiful life in poverty, she also gained an instant son right at his rebellious period.

Ten or so more years from then, the son would turn into a twisted, evil villain. He would appear in one of the extra chapters to pick on the male and female lead’s children.

***

Su Ran: Son, you shouldn’t be too outstanding.
Su Han: Why not?
Su Ran: ’cause you will be killed.

Su Ran: Son, would you like to learn music from me and become a zen, little fairy boy who only needs to drink dew.
Su Han: No, I want to go into business so I can support you.

- Description from Novelupdates

…but it seems pretty doable.