My Only One (2018)

Many many similar tropes; the family, the work, the coincidences, the rich man/poor woman, ...
Same writer, even similar characters names, common actors
The same cliches. You’re going to like the other if you like one

The main character: a poor girl who was kicked out by a mean mother. She welcomes a grandmother with dementia, she meets her "arrogant" grandson (not so arrogant in MOO) and you know what follows.
In my opinion, the acting is better in Shining Inheritance but being a family drama gives My Only One a good point. Each character has its own plotline (though everything intertwines somehow) instead of one couple solving everything (SI).
Careful, My Only One is pure makjang while SI emphasizes more on business.

Female lead with lost parents.
Multiple younger and older cute couples everywhere!
OSTs have the same vibe.

The dramas are very similar in that they both deal with overbearing families, both dramas have a grandma overseeing things, and both have lots of shady things done by characters to backstab each other, get ahead in life, etc.

Family dramas. They give a similar feeling. Also there is who keeps a secret in order to protect the one they love.

Both shows revolve around different families and their relationships and feature multiple couples. Lots of family secrets to reveal in both dramas. They also focus on the relationship between parents and children.