Fast Move
Out of ABC and CBS, NBC was the least successful network in the 1970s. In 1977-1978, there were a total of 30 network shows–only four of which were on NBC.
Diff’rent Strokes quickly became a success after it premiered in 1978, and the network decided to capitalize on this by creating a spinoff show called The Facts of Life. To make the story believable, Charlotte Rae (Mrs. Garrett) appeared on both shows simultaneously for a while.