No offense to Mackenzie Phillips, but why did she demand top billing on the show? Was she a star before ODAAT? I don't get it?

http://www.imdb.com/title/tt0072554/trivia

...welll she was on drugs.

Second billing was the best she could hope for. After all, Bonnie Franklin was the show's leading lady, not Mac, important though she was to the series.

The only thing she was on before ODAT that was big was American Grafitti and she wasn't the star of that movie.

AG was much more of an ensemble piece. The biggest star of the bunch at that time had to be Ron(ny) Howard - though there were plenty of up and comers in that cast.

You have to remember that Mac grew up the child of a rock star father. She was probably used to getting whatever she wanted. Including booze and drugs. And the booze and drugs would have certainly affected her judgment.

...welll she was on drugs.

Yeah, I gotta go with rob on this one.

No offense to Mackenzie Phillips, but why did she demand top billing on the show? Was she a star before ODAAT? I don't get it?

http://www.imdb.com/title/tt0072554/trivia

Well, this page does say REPRESENTATIVES squabbled over who should get top billing.

But after reading this whole page, I question the validity of some of these. The last one says

Bonnie Franklin, resented Glenn Scarpelli's performance because, he had more laughs than her. Finally, Scarpelli's character decided to go to college, and that lead to his departure

Didn't they say in the season 9 opener that Alex went to be with his mother in France or something like that?

I guess because of her Dad? I don't know.