Pedro is the brother of Juan, making him the uncle of Juan's children. Thus, Pedro is Maria's uncle and Carlos's uncle. Since Ana is the mother of Maria, but there's no information on Ana being married or related to Juan or Pedro, Ana would only be connected to Pedro by the fact that Ana's child, Maria, is Pedro's niece. Therefore, Pedro does not have a direct family relation to Ana (like brother-in-law) unless there's an unstated marital or co-parenting relationship. Ana would then be the mother of Pedro's niece, Maria.
If Pedro is the brother of Juan, and Juan is the father of Maria and Carlos, and Ana is the mother of Maria, what is the relation of Pedro to Ana, Maria, and Carlos?

Provide a very brief response.