Little House on the Prairie (1974)

S5E14 The Godsister

In this episode featuring twins Lindsey and Sidney Greenbush, Charles accepts a position with a telephone crew in southern Minnesota, leading him to be away from home for a few weeks. Carrie, feeling sad about her father's absence and yearning for companionship, finds herself getting in everyone's way. To cope with her loneliness, she invents an imaginary friend named Alyssa, who helps alleviate her heartache.