November 7, Thursday2 p.m. – International Space Station Expedition 63-64 Crew News Conference (All Channels)
Cassidy, Babkin and Tikhonov will arrive at the station as NASA flight engineers Jessica Meir and Drew Morgan, along with Expedition 62 commander Oleg Skripochka of Roscosmos, wrap up Expedition 62. When Meir, Morgan and Skripochka depart the orbital outpost, Cassidy will become commander of Expedition 63. He and his crewmates are expected to remain aboard the station until October 2020.
Who is the backup of Cassidy ?
I asked Rob Navias. His answer was"They (Cassidy, Tikhonov and Babkin) will be part of Exp. 62 for 8 days (launching on April 9) until Skripochka, Meir and Morgan undock on April 17 at which point they become 63."
So will they officially be the Expedition 62/63 crew or will they transfer over to Expedition 64 later in their mission.
So the Nasa does not expect that astronauts with Dragon or Starliner arrive at the ISS until April 2020.