Did anyone else notice that characters like Dr. Stevens and Rowan just disappeared? They were Guest cast but only show up in like 2 episodes.So whatever happened to them? Did they end up being background characters and stayed in Woodbury all the time? And did they stay in Woodbury only to join the group in the bus and we just didn't see them?

Also for Season 4, if Dr. Stevens did migrate to the prison, she could evolve more into guest cast because of her medical profession. 

Edit: Other missing characters like Eileen and Noah. Where the f*** did they go!?