Jennette

 was a member of the Blue Collar (Utility) class on a train-city on a devastated planet. Her father was Mr Villeharduin and her brothers were Burdine and Guillame.

Jennette and her brothers found Nyssa when she appeared in their compartment. At first they threatened her, but when they learned she was from off-world, they wanted her help for their rebellion.

In reality, Jennette and the entire train-city were part of an illusion that Maya had created for the Fifth Doctor and Nyssa. (PROSE: Confabula)