What is the main conflict in City of the Beasts by Isabel Allende?

Alex is fifteen the year his mother becomes gravely ill. When Alex's father, John, finds possible treatment for his mom in Texas, Alex and his two sisters are told they'll be sent to stay with their grandmothers. Alex's sisters will stay with their mom's mother, Clara, but Alex is to go to Kate, his dad's mother. Alex is furious with the decision, saying that Clara will cook and take care of the children, but Kate is unorthodox. Alex pleads to be allowed to stay with Clara, but John says three children will be too much for their grandmother. Despite Alex's pleas, he's sent to New York where he's to meet up with his grandmother prior to a trip to the Amazon.