Family Ties (1982) : 6x22

As Steven goes thru another one of his dreaded "magician phases" and tries to rope the whole family into participating in his magic tricks, the Keatons get a visit from Evelyn Mitchum, a former neighbor now living in New York, whose daughter Rosalie was beat friend with Mallory in junior high. The family is delighted to welcome Evelyn, but the tragic suicide of her daughter a year earlier makes for some awkward moments when they reminisce about old times. Sensing that Evelyn may need someone to confide in, Elyse makes a gentle but unsuccessful attempt to get her to open up about her devastating loss. When Evelyn turns her attention almost exclusively to Mallory, first inviting her to lunch, then on trips to the mall and the museum, Elyse begins to suspect that Mallory has become a surrogate Rosalie for Evelyn and warns Mallory she may get hurt. But Mallory insists she can and must handle the situation herself.