In both dramas there are:

Two male characters both linked to the same Chaebol,
Two female characters
The chairman of the Chaebol is the same actor in both dramas.

Also there are some similarities with the plot :
The husband of one of the female characters dies in a car accident early on, the Chaebol is
involved.
One of the female characters founds herself with a child that to take care of.
The female characters who takes care of the child ends up working in the Chaebol.
The female characters with a child has a big family to rely upon, they are the side characters.