Sister John, born Sarah Ann Coates, was a resident of the Home and is now running it.  
2015, around the same age as Joshua Valienté, Sarah was a resident of the Home and was one of the kids Joshua helped to get home on Step Day.
Twenty-five years after Step Day, now grown up, Sarah went back to the Home and took the name of Sister John.
She is seen at
Lobsang's garden party where she was tasked of taking care of a ill Monica Jansson.
May 2041, she is now running the Home. We see her with Joshua Valienté at the Home, now in Madison West 5 after the Madison bombing in 2030, watching President Cowley inaugurate the new Capitol on TV.
fall 2045, she greeted Joshua and Sally at the Home when they came to visit Lobsang. It was the day Lobsang died.
1.0 1.1 The Long Earth - Chapter 3
2.0 2.1 The Long War - Chapter 68
3.0 3.1 The Long Mars - Chapter 1
↑ The Long Utopia - Chapter 1