The prominent lawyer had been in failing health after a series of strokes.
The country singer, who was on Team Blake and finished as the Voice season 12 runner-up in 2017, shared the news of Janis Duski's death on Instagram.
The actor scored a No. 1 hit in 1976 with his soft rock ballad.
The stage and screen actor starred as Mrs. Banks in the 1964 Disney musical and won a Tony for starring in A Little Night Music on Broadway.
Fead launched his career in the music business after a chance meeting with a Liberty Records executive at a party.
The consummate Las Vegas lounge headliner passed away of natural causes on Dec. 31.
'The Smothers Brothers Comedy Hour' pushed the boundaries of network television in the '60s -- and was canceled before its contract was over.
"Life wasn't fair to you, that I know," her sister Angel wrote in a tribute.
"We hold a special place in our hearts for the time we spent playing music, laughing and traveling together," the country group, which now goes by The Chicks, wrote.
The Bronx native joined the Santa Monica-based public radio station in 1977 when it had five employees and the oldest transmitter west of the Mississippi.
