Rios daughter played the Orange Bowl 12s this year in Coral Gables/Miami, she is 10 but she played 12s. According to the Chilean media she had a knee wrap but played anyway and lost first round like 3 and 4. She apparently lives in FL with the first wife of RIos who went to NBTA and was, according the this Marcelo Rios book, good friends with Maria Sharapova. Also according to the Chilean media, MArcelo is not too keen on Costanza playing so many tour tournaments at such a young age - she also plays some USTA junior events in FL - but - but the mom presumably is the one calling the shots.
Facing Federer book was called "pretty addictive" by Steve Tignor :)