Guard at the Citadel wouldn't let us in, but said a scribe had given Cheryl the medicine at least two weeks ago and sent her along to the Rangers.”— Manny Koch
Cheryl is the sister of Manny Koch in 2277.
Finding her is the objective of the search party from Canterbury Commons in the unmarked quest Searching for Cheryl. She was never found, with the whole search party including her brother being killed.
Cheryl is mentioned only in Fallout 3.