Hi and welcome!
Two zones, which means:
Price is free for children under the age of two, maximum two children per adult and if they don't use a seat.
For groups of 10 or more people:
- Children with an age between 4 and 11 years old (both inclusive), have a 50% discount.
- Children of 12 years old in advance have a 30% discount.
Looks like you have to ask for permission at: 952 12 80 79.
Got the information from:
http://www.renfe.com/viajeros/cercanias ... entos.html