Sidoo, 59, was a 2016 recipient of the Order of B.C.
Loughlin and her husband allegedly payed a $500,000 bribe to have their two daughters, the elder of whom is a YouTube star and social media influencer, labeled as rowers to get into the University of Southern California.
Giannulli appeared in court on Tuesday and was released on US$1 million bail.
The scandal also ensnared movers and shakers in the corporate world.
Huffman later appeared in court, and was set free after posting $250,000 bail. Shares of the hedge fund plunged 9 percent.
Riddell didn't return several phone calls seeking comment.
William Rick Singer, from California, had been investigated for over a year and is alleged to have used bribes to help parents gain their child admissions, according to court documents.
Prosecutors said that parents paid Singer big money from 2011 up until just last month to bribe coaches and administrators to falsely make their children look like star athletes to boost their chances of getting accepted.
Some parents spent hundreds of thousands of dollars, as much as $6.5 million, to guarantee their children's admission, officials said.
Prosecutors said that on a call with one parent, Singer summed up his business thusly: "What we do is help the wealthiest families in the USA get their kids into school ... my families want a guarantee".More news: Governor Newsom to Halt Death Penalty; President Trump Is Not Thrilled
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At least nine athletic coaches and 33 parents were charged.
According to an indictment filed on Tuesday by the United States Attorney for the District of MA, the actress, her husband Mossimo Giannulli and dozens of other parents - including Desperate Housewives vet Felicity Huffman - allegedly bribed college entrance-exam administrators to allow cheating on the tests and university athletic coaches to designate school applicants as athletic recruits, regardless of athletic ability or experience playing a sport.
Huffman did get some support Tuesday from playwright and longtime friend David Mamet. Her husband, actor William H. Macy, has not been charged, though an Federal Bureau of Investigation agent stated in an affidavit that he was in the room when Huffman first heard the pitch from a scam insider.
Some of the most prestigious and exclusive higher-education facilities in America, including Stanford University, Yale University, and UCLA, were allegedly targeted by the scheme. Macy was not charged, but authorities did not say why.
Fuller House star Lori Loughlin is among the defendants.
A Hallmark Channel spokeswoman said the network hasn't decided what effect, if any, her arrest will have on programming.
Stanford's sailing coach John Vandemoer pleaded guilty Tuesday in Boston.
Three other cooperating witnesses, including a former head coach of women's soccer at Yale, have agreed to plead guilty, prosecutors said.
No students were charged, with authorities saying that in many cases the teenagers were unaware of what was going on.
All students involved in the college admission scandal should be removed from the institutions they fraudulently gained admissions to and their parents should serve jail time, according to Campus Reform's Lawrence Jones.
Many other cases involved photo fraud, according to Lelling.