. ♪ >>> pam dawber, by the mid-'80s, was a household name.williams in "mork and mindy." ♪ which was a massive hit in the late-'70s, early-'80s. >> who are you? >> i am mork from ork. nanu nanu. >> in addition to her sitcom fame, pam dawber was dating mark harmon, who she would go on to marry. he was on a show called "st. elsewhere" playing a doctor. he was "people" magazine's sexiest man alive in 1986. they were primetime television royalty. >> in 1986, pam dawber was in the market with a new sitcom that was eventually going to be called "my sister sam.” and pam dawber needed a kid sister to play opposite her. >> we searched and searched and searched for that patti character. and then, at the end, we became so desperate because we just weren't finding the right person. when rebecca came in, it was just clear she was the one. >> hi, i'm patti russel and this is my sister sam. >> i just moved in. >> we haven't lived together since we were kids. >> i was raised by our aunt and uncle. >> things sure have changed. i used to dress her. i can't wear