You’ll want to look into the AttachToActor and DetachFromActor nodes for this. You can call AttachToActor on the player to attach it to the ship when you possess the ship, and then call DetachFromActor on the player to detach if from the ship when you repossess the player.
The attachment rules on both nodes should all be set to Keep World so the player’s world position will follow the ship properly. Weld Simulated Bodies should be turned on for AttachToActor because it will lock your player to their spot in the ship and prevent them from sliding around.