Originally, in early versions of Resident Evil: Revelations (Notably the Pilot 3DS Demo) Rachel did not appear, in her place there was another male character known as Richard, who was also going to have a similar role as Rachel, leaving a diary/memo behind and stalking the player later on after mutation, It is unknown if Rachel had a different role at this point.
TGS 2011 Reveal and final game
In 2011, Rachel made her debut in the TGS 2011 Trailer for the 3DS Version, which featured never before seen footage which doesn't even appear in the released game, an Extended version was released shortly after. She was then listed as a character in the website for the game and artworks were released for her.
She was then briefly featured in Jessica's Report in which she was seen as a playable character for the first time, despite not being playable in the 3DS Version.
In 2013, for the HD Edition / Unveiled Edition, Rachel was added as a playable character in Raid Mode and given the surname "Foley"
Along with that, an Ooze Rachel version was also added to Raid Mode.