Michael Rogers, 53, from Romford, Essex, was also found guilty of 14 counts including cruelty, rape and inciting a child to engage in sexual activity.
Jason Adams, 43, from Norwich, was found guilty of 13 similar counts.
Carol Stadler, 59, from Norwich, was found guilty of assault causing actual bodily harm but cleared of nine other charges, including serious sexual assaults.
The remaining defendants - Anthony Stadler, 63, Nicola Collins, 36, Andrew Collins, 52, Judith Fuller, 31, Denise Barnes, 43, and Kathleen Adams, 85, all from Norwich - were cleared of all counts.
Prosecutor Angela Rafferty QC said Black, previously known as Marie Adams, played an instrumental role in using the five children as "sexual play-things".
The abuse, which is said to have happened in and around Norwich and London, included forcing the children to have sex with one another.
On some occasions, the adults threw parties and played card games to decide who would abuse which child, Mrs Rafferty said.
In interviews the victims described how they were abused in front of one another and other adults.
They said the abuse became so routine the victims came to accept it as normal.
Describing Black, Mrs Rafferty said: "Was she a helpless victim of abusive males or was she herself deeply involved with the children's ill treatment?
"Many of the defendants have become good at appearing normal and respectable.
"This is what you would have to do in order to be child abusers to the extent alleged here."
All of the defendants denied abusing the children, and claimed it simply did not happen.
Speaking outside the court, Detective Chief Inspector Pete Hornby praised the bravery of the victims and said he was satisfied with the result of a 28-month investigation.
"This case provides a sickening glimpse into sexual abuse on a large scale," he said.
"It is the most harrowing case I have dealt with in 23 years of policing.
"Marie Black has been found to be at the centre of this abuse and incited others to commit abuse against them. She thought they would never speak out.
"Today's verdict is testament to the children's bravery and to the hard work of dedicated professionals from a range of agencies in this case.
"It has brought them the knowledge they are believed and, I hope, will encourage other victims of abuse to find their voice and come forward."
- Daily Mail
