Twelfth Doctor
Author Gary Russell had planned to use River in the Twelfth Doctor novel "The Big Bang Generation", but when he was unable to get permission to use her due to Steven Moffat planning on the 2015 Christmas special "The Husbands of River Song" being the Twelfth Doctor and River's first meeting, Moffat suggested that Russell write the story to incorporate the Seventh Doctor's former companion Bernice Summerfield instead.