Forgotten Title Rebirth novel - Know everything but the title!

Not so long ago I remember reading and finishing this novel and remember even mtl-ing it near the end!
I have an urge to re-read it and have completely forgotten its name.

It was about how the MC's sister (who knows modern stuff like the formula for cement and glass) had in the first life rejected the 'useless partying' husband, and that husband got passed down to the MC (who, I think, was an illegitimate child - or was it half-sibling? well, something like that). This pair of husband and wife (MC) ended up with the 'useless' husband becoming a high ranking official and the emperors right hand, while the MC sister went into the imperial harem of the pretty old Emperor and lived a terrible life.

Now in this life, the MC's sister (who is reborn) decided to keep her marriage with the 'useless' husband, and accidentally ends up arranging a marriage with a handsome official son guy who is, essentially, the marriage material person of all the girls in town, to the sister (MC).

You might've guessed, but the handsome cold guy falls in love with the smart MC, and rises up in position, and later on, the marriage with the 'useless' guy also gets broken and he marries someone else (that person who ends up being ..- wait, I feel like that's a spoiler), while the MC's sister eventually goes into the imperial harem (again), and well, she has a bad life again.

The actual summary of the novel is probably found within the first two paragraphs, but yhhh, I'm in one of those situations where I know everything except for the actual title :?


Anyway, please do let me know if you have any inkling about what this novel was called!


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Can't link (not enough posts) but should be:

Transmigrating into the Female Supporting Character with a Good Life in a Laid-Back Novel

...though I had it saved under the title of "braised duck".

 

Foodie lol