They are not actually real siblings. Eventually there will be a change of relationship. Similar in terms of how main characters’ relationship.

Premise are similar with Fl lead and Ml lead, how the male lead is adopted into the female lead's family. Not real siblings.

Dashing Youth has similar antic as I am Nobody, with the characters and direction of the drama. It is like I am Nobody is the modern version of Dashing Youth and Dashing Youth is the historical version of I am Nobody.

Both touches on music. Both female leads have passion for music but their family are against it, claiming it is an unrealistic dream.

"Love is Sweet" and "Only for Love" are both Chinese romance dramas that focus on the relationships between the main characters. Both dramas deal with themes of love, ambition, and the challenges of navigating relationships in the modern world. However, the specific plot details and characters in each drama are likely to be different, and it is up to individual viewers to decide how similar or different they perceive the two dramas to be.

They both have similar setting, which is around an office/business romance. The similarity between these two dramas lies in their premise of a female lead who has a close professional relationship with a successful and powerful male lead. Plus, both dramas share similarities in their portrayal of a workplace romance.