Like other Lear productions such as "All in the Family" and "Good Times," ''One Day at a Time" dealt with contemporary issues once absent from TV comedies such as premarital sex, birth control, suicide and sexual harassment — issues that had previously been overlooked by TV comedies whose households were usually headed by a husband and wife or, rarely, a widowed parent.
Writing in her 2009 memoir "High On Arrival," Phillips remembered Franklin as hardworking and professional, even a perfectionist.
"Bonnie felt a responsibility to the character and always gave a million notes on the scripts," Phillips wrote. "Above all, she didn't want it to be sitcom fluff — she wanted it to deal honestly with the struggles and truths of raising two teenagers as a single mother."
In her 2008 memoir "Losing It," Bertinelli noted that Franklin, just 31 when the show began, wasn't old enough to be her real mother.
Even so, wrote Bertinelli, "within a few days I recognized her immense talent and felt privileged to work with her. ... She was like a hip, younger complement to my real mom."
The truth of "One Day at a Time" was brought home to Franklin when in 2005 she got together with both TV daughters for a "One Day at a Time" reunion special. She told both actresses, "You are living, in a sense, Ann Romano's life — you are single parents raising teenage kids. That is shocking and terrifying to me."
Bertinelli reiterated Friday that Franklin was a "second mother to me" and one of the most important women in her life.
"My heart is breaking," Bertinelli said in a statement. "The years on 'One Day At A Time' were some of the happiest of my life, and along with Pat and Mackenzie, we were a family in every way. She taught me how to navigate this business and life itself with grace and humor, and to always be true to yourself. I will miss her terribly."
Lear noted that despite tackling some serious subjects in her work, Franklin always stayed cheery and positive.
"I was wrong — I thought life forces never die. Bonnie was such a life force," Lear said in a statement. "Bubbly, always up, the smile never left her face."