I read on different site that they use SSL as well. So, she could probably learn either one.
"Who Uses Spanish Sign Language?
Andorra, Argentina, Belize, Bolivia, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Gibraltar, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Spain, and Venezuela are the Spanish-speaking countries of the world. In most of these countries, national associations of the deaf have published sign language dictionaries. Many of the dictionaries listed below were found on the Gallaudet Library page "Sign Languages of the World, by Name," and others were from the International Bibliography of Sign Language. Population data came from Ethnologue. Some countries are too small to have their own native sign language and are instead utilizing American Sign Language (ASL) or something close to ASL."
Sign Language - Sign Languages Used in Spanish Speaking Countries