The Goal Is to Become a Gold Spoon so I Need to Be Completely Invulnerable

“I was born with a gold spoon in my mouth but I’m being murdered miserably? I’ll survive thoroughly and live a long life!”
I’ve been reincarnated as the younger sister of my favorite’s novel character who is destined to be poisoned by her step-mother at the age of seventeen. My brother is on an adventure with the heroine so I have to survive by myself. Should we start with survival plans? First, be sure to behave myself around my step-mother and step-sister. Secondly, become close with children of influential families. Third, is… umh… getting married?
To escape the fate of a miserable death, I, Adriana, begin to approach the Prince of the Empire, the suspicious Master, and the suspicious Demon!