BC is not an agent, that is, they don't work for or represent the talent. They work for the producers. (A talent agent works for and represents actors.) They cast for movies and commercials. You can go on their website and follow the section about how to put yourself in their database. If a producer comes to them looking for a 1 year old, BC will look through their database for people to come in and audition.
There is no age requirement. It depends on the casting call.
Boston Casting has casting calls for all ages. I don't know about requirements for babies.
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