Legally, Dad (2020)

Both are mini dramas in which the ML and FL agree to a contract relationship as relatives (brother and sister vs. father and daughter) for the ML's need to please a relative, and while living together they fall in love.

Both are mini dramas with a contract relationship (relatives vs. marriage) between the main couple that grows into true love.
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Both are mini dramas in which the ML and FL agree to a contract relationship as relatives (brother and sister vs. father and daughter) for the ML's need to please a relative, and while living together they fall in love.

Both dramas involve the ML and FL entering into a contract relationship as relatives (siblings vs. father and daughter) which leads to romance.

Both dramas have the odd concept of the main couple pretending to be relatives (brother and sister vs. father and daughter) and living together. Both lies stem from helping/protecting the ML (letting him keep his business vs. protecting him from the law). Both dramas are quite short.

Both are mini dramas with a poorer FL who is raising her little relative (nephew vs. little sister) alone, and a wealthy ML who moves in with the FL due to needing/wanting the child (to keep his business vs. fulfill his father's wishes). Both have a super cute supporting child actor who likes the ML right away, and both main couples have a somewhat antagonistic relationship at first that quickly warms to romance.