Segundo Marido (2021)

Both have a similar plot (hidden identity, marriage with hidden motive, betrayal, etc)
Same actors playing the female antagonist & FL’s mother role

Both dramas are makjang however, that sun in the sky doesn't focus on revenge and on the other hand Second Husband is more on revenge.
Both dramas have the female lead encountered betrayal by her lover by marrying a rich woman to replace the female lead and the male lead will do anything up to extent for his selfish success!

Both are revenge kdramas. The series follows Kang Yi-kyung, a woman whose father is a murderer. She must deal with tough times i.e. her boyfriend leaving her, her family which adopted her also left her and she was harshly treated because she was a murderer's daughter so she plots her revenge. To fulfill her revenge, she assumes another woman identity and comeback as Seo Jung-ha.

Same evil villian type ex husband, who has a new woman and is ganging up with her to make his wife's life misearable in every way possible
and by same evil villian type ex, - i mean the same actor is playing the role in both shows...
he is more fun in Woman in the Veil and more serious in Second Husband, but a cheater and all round bad guy all the same...
always the husband's new woman is in the right place to know all the secrets and create havoc!
also has hidden identities...
is she blind or isn't she blind - the mother in Second Husband had that..
anyways... all the makings of this type of drama and if you enjoyed the chaos of one you would also enjoy the chaos of the other