Adie struggled with alcoholism and mental illness, and was reported to be abusive; at one point in her film career, Foster rented the home of actress Jean Arthur for her younger sisters, in an attempt to get them away from their mother.

[7] Within weeks of leaving Paramount, Foster signed with Universal Studios, where she portrayed the ingénue in the 1943 film version of the Gothic melodrama Phantom of the Opera opposite Nelson Eddy and Claude Rains.

She became so popular the studio set her on a meteoric rise with back-to-back pictures during the years 1943 to 1945, including Star Spangled Rhythm, Top Man, This Is the Life, The Climax, Bowery to Broadway, Frisco Sal, and That Night With You.

Desperate to hold onto its star, Universal sought to make her dream of grand opera come true, financing a six-month tour of a post war Europe in 1946 with Dusolina Giannini.

In 1946, Foster accepted the lead role in the Los Angeles Civic Light Opera's production of Naughty Marietta headed by Rodgers and Hammerstein associate Edwin Lester.

[14] During the London engagement their second son was born, brought into the world by Queen Elizabeth's doctor, John Peel, who also attended in the births of others to the Royal family, including Prince Charles and Princess Anne.

In November 1985, Philip – who also struggled with alcoholism as well as drug addiction – lapsed into a hepatic coma on Foster's living room floor and died three days later in the Van Nuys Hospital from liver failure.

[18] In 2003, her elder son Michael brought her back to the East Coast, where she spent the last five years of her life living at the Lillian Booth Actors Home in Englewood, New Jersey.