Mermaids (Merling Queen's)
From A Wiki of Ice and Fire
The Mermaids are four attendants of the Merling Queen, a courtesan in Braavos. She is never seen without her Mermaids to hold her train and do her hair. The Mermaids are young maidens in the blush of their first flowering.  One of the Mermaids drowned at some point.
A Dance with Dragons
The Merling Queen has chosen a new Mermaid to take the place of the one that drowned. She is the daughter of a Prestayn serving maid. She is thirteen and penniless, but lovely. The Kindly Man replies that they are all lovely, at the beginning.