"They're happy she's safe and that Amanda is finally getting some help," a source tells PEOPLE.
The troubled actress, 28, who flew from New York to L.A. on Friday after exhibiting increasingly disturbing behavior in recent weeks, was involuntarily admitted shortly after touching down in California, PEOPLE confirmed.
Believing she was being chauffeured from the airport to a lawyer's office for an appointment, a blindsided Bynes was instead driven to a Pasadena treatment center, where she remains as of this morning.
The flight and intervention were part of a plan hatched by her parents and their attorney, Tamar Arminak, to get Bynes help, PEOPLE has learned. (Also playing a key role was Sam Lutfi, a former Britney Spears confidante who recently befriended Bynes and helped orchestrate the cross-country flight.)
"It was touch and go whether the plan would work," says the source, adding that currently Bynes "is erratic and disconnected from reality."
Indeed, in a series of rambling revelations to reporters and on social media, she recently proclaimed she was engaged, needs a "tremendous amount of facial surgery" and "will not be manipulated or brainwashed by anyone."
Last week, the former child star took to her Twitter account to make alarming accusations, including claims that her father was sexually, verbally and physically abusive when she was younger.
Although she subsequently deleted the Tweets about sexual abuse and blamed "the microchip in [her] brain" for making her lash out, it was not the first time Bynes has targeted her father.
"When she is in one of these states, her anger and frustration is directed towards her father," says the source.
In response to the accusations, Lynn Bynes, who has remained largely silent about her daughter's troubles, issued a statement to PEOPLE through her attorney Arminak, refuting the claims and citing her daughter's "mental state" for the charges that "have no basis in reality."
Likewise, Bynes's siblings, Jillian O'Keefe and Tommy Bynes, rushed to their parents' defense.
"We are disturbed beyond words that Amanda would come up with such a fabrication as a way to avoid getting much needed help or treatment," they told PEOPLE, via Arminak.
"We have the most wonderful parents who have ever lived [and] are pained by [Amanda's] behavior. … We absolutely give our full unconditional love and support to our wonderful parents."
Chillingly Similar to Previous BehaviorBynes's behavior was chillingly similar to a series of episodes in the summer of 2013, which culminated in her being hospitalized on her first involuntary psychiatric hold. After a period in treatment, the actress was placed under her mother's care and lived with her parents in the L.A. area.
At the time, a close source said her parents were optimistic that she was healing.
"They hope ... Amanda's situation will get under control," said the source. "They love their daughter very much."
This time around, Bynes's parents are no less committed to their daughter. "They have not turned their backs on her," says the source.
On Monday afternoon, PEOPLE confirmed that Bynes's psychiatric hold was extended two weeks. She will remain in treatment.