So while watching the new series Suspicious Partner I found that I was trying to think of other dramas that had a main/second lead female that cheated and wanted to get the main lead back.  Anyone happen to remember any?

Also, anyone know of any dramas where the male or female lead finds out they have a older or younger sibling?

a female lead cheating is not usually a desirable trait for a character. It seems that male characters get away with it better but it is also hard for them to be redeemable. Cheaters: 
I need Romance (the male lead cheats but wants to stay together with female lead).
I have a lover (male lead cheats, female lead goes through a lot and has to decide if she wants to stay together).
Greatest Marriage (male lead gets female lead pregnant and also gets 2nd female lead pregnant it's a very messy and strange storyline)

siblings:
Triangle Korean drama (Long lost brothers).
2nd lead Cheaters:

Shitsuren Chocolatier
Best Lover


Found out they have a sibling:

I'm sorry I love you
Best lover
Atashinchi no Danshi
Bloody Monday
Summer's desire
49 Days ---> falls under both the categories 

Yes, I have seen plenty male cheaters.  That's why I started trying to think of shows I have seen with female cheaters, mind you trying to recall everything that happened in every drama I have watched is getting more difficult.  

As far as the sibling thing is concerned, I know of a few and I will check out the ones suggested.

Any series where the siblings know about each other, but haven't really interacted is welcomed as well.  For instance, Doctors.

There is a series where I remember the mother coming to the daughter for money, and you only find out later that she has another daughter and the money is for her treatment.  I can't remember what the series was though.