Zhao Li Ying's character is a daughter of the merchant (she's either the youngest or the 2nd to youngest), but she was raised as a maid....it has to do with who her mother is, but that's going to be revealed in future episodes. I can't recall if everyone knew she was the merchant's daughter or not in the beginning, but she knows, the merchant knows and I think the 1st wife knows as well.
This is a really adorable but somewhat improbable show. I quite enjoy it...Zhao Li Ying and the eldest brother has great chemistry...also, him being sooo very tall and her so small allows for a lot of great princess-carry scenes. For a show that is set in the ancient chinese timeframe, this show allows for a lot of modern "intimate" scenes, which is both strange but amusing. I like part 1 more than part 2 just because the oldest couple is my favorite of the 3, but part 2 is still watchable.
Both part 1 and part 2 are fully eng subbed on
http://www.viki.com/
Just search
Cuo/Xi Dian Yuan Yang