Question: When does meredith find out pierce is her sister?
Disambiguated questions and answers: question: What is the name of the episode where Meredith finds out Pierce is her sister?
In what season and episode number did Meredith find out that Pierce is her sister?
In what overall episode number did Meredith find out that Pierce is her sister?
What is the date of the episode where Meredith found out that Pierce is her sister?
answer: Fear (Of the Unknown)
Season 10 Episode 24
220
May 15, 2014
Natural Questions answer: the season ten finale (from the Wikipedia article "Maggie Pierce")