Alison Carey, 55, was arrested on prostitution charges earlier week at a low budget motel in upstate New York. She has pleaded not guilty.
Cops say she placed an online ad soliciting sex that borrowed lines from her sister's 1996 hit, "Fantasy."
See photos of Mariah Carey through the years:
Mariah Carey through the years
Mariah Carey through the years
FILE--Singer Mariah Carey displays the two American Music awards she received for favorite pop-rock female artist and for top adult contemorary album of the year for her "Unplugged" recording in this Jan. 26, 1993 file photo. Carey and Alanis Morissette, the young Canadian singer, got six Grammy nominations each Thursday, Jan. 4, 1996. (AP Photo/File, Reed Saxon)
Pop singer Mariah Carey displays her two awards for the best pop-rock female artist and best female in the soul rythym and blues categories during the 23rd annual American Music Awards at the Shrine Auditorium in Los Angeles, Monday, Jan. 29, 1996. Carey won awards for favorite female artist for "Pop and Rock" and "Soul/R&B." (AP Photo/Chris Pizzello)
Mariah Carey performs the opening song with Wanya Morris of the group Boyz II Men at the 38th annual Grammy Awards at the Shrine Auditorium in Los Angeles, Wednesday, Feb. 28, 1996. (AP Photo/Eric Draper)
US American singer Mariah Carey during her only concert in Germany on Friday evening, June 14, 1996, at the Frankfurt "Festhalle" auditorium. About 12,000 fans attended Carey's start of her "Daydream" tour through Europe. (AP Photo/Bernd Kammerer)
Mariah Carey performs a benefit for the Fresh Air Fund at the Cathedral of St. John the Divine in New York Thursday, Dec. 8, 1994.(AP Photo/Ron Frehm)
Mariah Carey sings at the "VH1 Divas 2000: A Tribute to Diana Ross" Sunday, April 9, 2000, in New York. (AP Photo/Ron Frehm)
Singer Mariah Carey arrives to a special screening of her first film "Glitter," Thursday, Sept. 20, 2001, in Los Angeles. Carey was attending the special screening with Make A Wish Foundation children. She portrays a rock star in the film. (AP Photo/Kevork Djansezian)
Mariah Carey makes a guest appearance during a benefit concert at New York's Madison Square Garden, Thursday, Dec. 13, 2001. Proceeds from the performance were to benefit various charities. (AP Photo/Chad Rachman)
Singer Mariah Carey arrives at the Island Def Jam Holiday party in New York, Thursday, Dec. 12, 2002. (AP Photo/Shawn Baldwin)
Mariah Carey does a television interview at the Fresh Air Fund Salute To American Heroes, at Tavern On the Green, in New York, Thursday, June 5, 2003. (AP Photo/Robert Spencer)
U.S. singer Mariah Carey arrives at the Cannes festival palace, to take part in the NRJ awards ceremony, during the Midem 2003 (International record music publishing and video music market), Saturday, Jan. 18, 2003, in Cannes, southern France. (AP PHOTO/Lionel Cironneau)
Mariah Carey, wearing a Michael Jordan (23) jersey from the Chicago Bulls performs during halftime of the 2003 NBA All Star Game in Atlanta Sunday, Feb. 9, 2003. (AP Photo/John Bazemore)
U.S. singer Mariah Carey smiles as she is welcomed by Italian designer Donatella Versace, at right, as special guest for her Spring/Summer 2004 fashion collection, in Milan, Italy, Saturday, Oct. 4 2003. Mariah Carey is presently on a world tour. (AP Photo/Luca Bruno)
Die amerikanische Top-Saengerin Mariah Carey posiert fuer Fotografen in Berlin am Freitag, 18. Maerz 2005. (AP Photo/Fritz Reiss) - - - U.S. top singer Mariah Carey poses for photographers in the German capital Berlin on Friday, March 18, 2005. (AP Photo/Fritz Reiss)
US singer Mariah Carey performs during the German television show 'Wetten Dass...?' ('Bet it...?') in Berlin Saturday March 19, 2005. '(AP Photo/Soeren Stache, Pool)
US pop star Mariah Carey waves as she arrives for the awarding ceremony for German music award "Echo" in Berlin on Saturday, April 2, 2005. (AP Photo/ Jan Bauer)
U.S. singer Mariah Carey performs during the German 'Echo 2005' music award ceremony in Berlin on Saturday, April 2, 2005. (AP Photo/Markus Schreiber)
U.S. singer Mariah Carey sings her single cut "It's Like That" during her promotional event in Tokyo, Thursday, March 31, 2005. Carey is here to promote her new release. (AP Photo/Junji Kurokawa)
Mariah Carey accepts the award for favorite soul /rhythm & blues female artist at the 33rd annual American Music Awards in Los Angeles on Tuesday, Nov. 22, 2005. (AP Photo/Mark J. Terrill)
US singer Mariah Carey poses in front of a poster of herself during a photo call for the award to recognise the global sales of seven millions copies of "The Emancipation of Mimi" presented in Munich, southern Germany, on Wednesday, Nov. 30, 2005. (AP Photo/Christof Stache)
Mariah Carey speaks to children at Madison Square Garden where "Peter Pan is being staged inNew York, Wednesday, Dec 7, 2005. Children from the Fresh Air Fund and winners selected by radio station WKTU were treated to a special holiday reading of " Peter Pan" by Carey. Mariah, who had a comeback year, is one of many artists who made some memorable music this year. So its unlikely that one name will dominate this year's Grammy nominations, which are to be announced in New York on Thursday morning. She'll also be one of the recording stars scheduled to read the nominations.(AP Photo/Stuart Ramson)
Mariah Carey performs at the 48th Annual Grammy Awards on Wednesday, Feb. 8, 2006, in Los Angeles. (AP Photo/Mark J. Terrill)
Singer Mariah Carey appears on stage during MTV's "Total Request Live" show at the MTV Times Square Studios, Wednesday, April 12, 2006 in New York City. (AP Photo/Jeff Christensen)
Singer Mariah Carey reacts to a skit at the 2006 ESPY Awards in the Hollywood area of Los Angeles Wednesday, July 12, 2006. (AP Photo/Chris Carlson)
Singer Mariah Carey holds her trophy during a taping for MTV's "Total Request Live Awards" show at the MTV Times Square Studios, Tuesday, Feb.21, 2006 in New York City. (AP Photo/Jeff Christensen)
Mariah Carey performs at Madison Square Garden on her "The Adventures of Mimi: the Voice, the Hits, the Tour," in New York, Wednesday, Aug. 23, 2006. (AP Photo/Henny Ray Abrams)
Singer Mariah Carey performs during her "Emancipation of Mimi" concert in Los Angeles on Friday, Oct. 6, 2006. (AP Photo/Matt Sayles)
Singer Mariah Carey arrives at VH1 Save the Music Foundation 10th Anniversary gala in New York, Thursday, Sept. 20, 2007. (AP Photo/Peter Kramer)
Mariah Carey is interviewed on the NBC "Today" television program in New York's Rockefeller Center Tuesday morning Oct. 23, 2007. She was promoting her fragrance "M by Mariah Carey." (AP Photo/Richard Drew)
Singer Mariah Carey launches her new fragrance "M by Mariah Carey" at Macy's Herald Square, Tuesday, Oct. 23, 2007 in New York. (AP Photo/Evan Agostini)
(AP Photo/Peter Kramer)
NEW YORK, NY - FEBRUARY 12: Singer Mariah Carey and Nick Cannon attend MTV First: Mariah Carey's 'You're Mine (Eternal)' music video world premiere at MTV Studios on February 12, 2014 in New York City. (Photo by Larry Busacca/Getty Images)
LOS ANGELES, CA - JANUARY 18: Mariah Carey and Nick Cannon (R) arrive at the 20th Annual Screen Actors Guild Awards at the Shrine Auditorium on January 18, 2014 in Los Angeles, California. (Photo by Dan MacMedan/WireImage)
NEW YORK, NY - AUGUST 05: Nick Cannon (L) and Mariah Carey attend Lee Daniels' 'The Butler' New York premiere, hosted by TWC, DeLeon Tequila and Samsung Galaxy on August 5, 2013 in New York City. (Photo by Kevin Mazur/Getty Images for Samsung)
HOLLYWOOD, CA - NOVEMBER 17: TeenNick Chairman and HALO Awards host Nick Cannon and singer Mariah Carey attend Nickelodeon's 2012 TeenNick HALO Awards at Hollywood Palladium on November 17, 2012 in Hollywood, California. The show premieres on Monday, November 19th, 8:00p.m. (ET) on Nick at Nite. (Photo by Charley Gallay/Getty Images For Nickelodeon)
NEW YORK, NY - DECEMBER 15: Mariah Carey leaves the Beacon Theater on December 15, 2014 in New York City. (Photo by James Devaney/GC Images)
LOS ANGELES, CA - MARCH 14: Mariah Carey (L) and actor Jussie Smollett attend the Human Rights Campaign Los Angeles Gala 2015 at JW Marriott Los Angeles at L.A. LIVE on March 14, 2015 in Los Angeles, California. (Photo by Jason Kempin/Getty Images for Human Rights Campaign)
NEW YORK, NY - DECEMBER 03: Mariah Carey performs at the 82nd Annual Rockefeller Christmas Tree Lighting Ceremony at Rockefeller Center on December 3, 2014 in New York City. (Photo by James Devaney/WireImage)
NEW YORK, NY - DECEMBER 03: Singer Mariah Carey performs at the 82nd Annual Rockefeller Center Christmas Tree Lighting on December 3, 2014 in New York City. (Photo by Paul Zimmerman/WireImage)
SHANGHAI, CHINA - OCTOBER 19: Singer Mariah Carey performs live during her 2014 China Tour on October 19, 2014 in Shanghai, China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)
NEW YORK NY - AUGUST 26: Mariah Carey sighting on August 26, 2014 in New York City. (Photo by Josiah Kamau/BuzzFoto/FilmMagic)
HOLLYWOOD, CA - JULY 23: Singer Mariah Carey and actor Dwayne Johnson attend the after party for the premiere of Paramount Pictures' 'Hercules' at the Roosevelt Hotel on July 23, 2014 in Hollywood, California. (Photo by Alberto E. Rodriguez/WireImage)
CAP D'ANTIBES, FRANCE - JUNE 17: Mariah Carey performs during Clear Channel Media And Entertainment And MediaLink Dinner at Hotel du Cap-Eden-Roc on June 17, 2014 in Cap d'Antibes, France. (Photo by Tony Barson/Getty Images for Clear Channel)
NEW YORK, NY - JUNE 09: Singer Mariah Carey announces the launch of her Go N'Syde bottle 'Butterfly' at the Saint Regis Hotel on June 9, 2014 in New York City. (Photo by Andrew H. Walker/Getty Images)
NEW YORK, NY - MAY 29: Singer Mariah Carey attends the 2014 Fresh Air Fund Honoring Our American Hero at Pier Sixty at Chelsea Piers on May 29, 2014 in New York City. (Photo by Monica Schipper/FilmMagic)
Mariah Carey performs during the World Music Awards at Monte Carlo Sporting Club, on May 27, 2014 in Monaco. (Photo credit: VALERY HACHE/AFP/Getty Images)
TODAY -- Pictured: Mariah Carey appears on NBC News' 'Today' show -- (Photo by: Peter Kramer/NBC/NBC NewsWire via Getty Images)
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"I'm a pretty lady looking for guys...with me it's such a sweet, sweet fantasy baby!" the ad read.
The arrest is the latest crisis for Alison, who in her younger days wanted to be a singer just like Mariah, but she ended up battling drugs and falling on hard times.
Morgan said: "I would hope Mariah could find it in her heart to forgive Alison her transgressions and step up, create a trust, let's make sure Alison's needs are met."
Morgan and Mariah were once very close. In fact, Morgan — a model and music producer — claims he was instrumental in Mariah becoming a superstar.
Mariah's publicist says she has done a lot over the years to give Alison a helping hand.
"Through the years, Mariah has spent hundreds of thousands of dollars supporting Alison and her children," the statement said.
Morgan says: "I will always be puzzled why Alison, a heroin addict, has always been given large sums of money from Mariah her whole life. You can't put large sums of cash into the hands of a drug addict."
Incredibly, Morgan fears retaliation from his famous sister and her fans for speaking out.
"It's about protecting this fiction she has created, this image she has created, it's about keeping the darkest secrets covered up," he said.
It is believed Mariah has not spoken to her sister since 1994.