1.  Trot Lovers - the FL is left to care for her much younger sister

2.  The Great Show (depends on whether you consider 18 to be adult - she has been left alone to care for her younger half-siblings)

3. To Love, To Heal - ML

4. My Secret Romance -FL

5. Hotman - ML is 29, his youngest siblings are 15.

Do adopted siblings count?

 NoirRoseHeart:

Do adopted siblings count?

yes, and half siblings too

6. Romance of the Little Forest

8. Stars Falling from the Sky

9. The King: Eternal Monarch

10. Reply 1988- sunwoo and jinju


10 dramas where the main leads "lose each" other and then meet after a long/short period of time

 (ex.cloy where they meet in south korea, then later in Switzerland) 

Sorry, I don't know what you mean about losing each other. In CLOY they each knew where the other was.  Are you referring to something more than a time apart?

1. Thirty But Seventeen - They had a crush on each other when they were kids then stuff happened and they find each other again later.

2. I Hear Your Voice

3. Meeting You - They were kids in preschool/kindergarten together then she moved away and found each other again in high school.

I know of 2 more but I'll only post if the topic stalls and it is close to 24hrs.

4. W (one of my favorite noble stupidity separation :D)

5. Oh My Ghost (she went abroad to study)

6.  Just Between Lovers

7. Come and Hug Me

(my spoiler flag isn't working for some reason, so I can't censor or provide the specifics, but both are more in the setup, so not major spoilers)

8. My Secret Romance

9. Chocolate