Cathy becoming an Exchange Student

Cathy thinking she was underfoot at the Lanes applied to be an exchange student in Argentina. Martin and Natalie signed and gave their permission for Cathy to go. But why wasn't Cathy's father involved with this decision? He is still her father, and the Lanes were having her stay to give Cathy a stable home while he was reporting around the world, and that she could have an uninterrupted education. The Lanes, I think, should have consulted Cathy's father before they all signed on the dotted line.