Sort:  

"Mary's father has 5 daughters" So she is the fifth since she named the other 4 daughters and it is her father who has the daughters...hehe.

Is NuNu a real name?

How come the fifth daughter got named Mary and not NuNu ?

You only foxed me in to answering because I thought I knew the answer - LOL
(I'm probably wrong about Mary ?)

I have a really low IQ, so not sure how you tricked me ;-)