first appeared as an American Indian child in the 1967 B-grade western Cry Blood, Apache at age 4.
In 1969, Lyn auditioned for the character Prudence on the short-lived ABC series Nanny and the Professor, but when the pilot did not initially sell, she was released from her contract with ABC. ABC unsuccessfully sued to get Lyn for the part after she'd already been cast for M3S.
Lyn worked steadily in her youth on many popular series like Adam 12, Emergency, Marcus Welby and Gunsmoke. In 1971 Lyn had a major role in the western Shoot Out as Gregory Peck's daughter. She also appeared in movies such as the Walking Tall trilogy. In 1973 Lyn auditioned for the role of Regan in The Exorcist, but was considered too young for the subject matter.
In 1974, Lyn appeared in the cult classic Devil Times Five, where Lyn's character Moe dumps a bucket of piranhas into a bathtub to creatively kill the character Lovely, played by Lyn's mother. (In Cry Blood Apache, the cowboy played by Lyn's father murdered the character played by her mother.)