Rizlaine, 22, was shot by police during a raid on a house in Willesden, north-west London on April 27, 2017 and was arrested when she was discharged from hospital three days later.
She later pleaded guilty to preparing terrorist acts, as did her mother, Mina Dich, 44.
Her sister Safaa Boular, 18, denied the charge but was convicted by a court at the Old Bailey in London on Monday, June 4.
She is the youngest woman ever to be convicted of an Islamist-inspired terror charge in the UK.
Police began tailing Safaa after she returned from a trip to Morocco in August 2016.
Safaa, who was 16 at the time, suggested she was planning to travel to Syria to join Daesh*.
Two days later her mother reported Safaa and Rizlaine missing but when they were arrested by police in London they said they wanted to live under Daesh in Syria but had no plans to commit terrorist acts.
Police seized phones and tablets from the pair and found Safaa had been in touch with a British national who was fighting for Daesh in Syria.
Planned To Marry Daesh Fighter
She was planning to marry him and also talked about wearing a suicide belt.
While she was on bail Safaa began discussing plans to get hold of guns and grenades so she could carry out a terrorist attack in London.
Safaa was subsequently charged on April 12, 2017 but her mother and sister then hatched their own plan to carry out an Islamist-inspired attack.
During phonecalls between the pair and Safaa they used a bizarre "tea party" code to the terrorist attack and at one point referred to Rizlaine as the "mad hatter", as in the character in the book Alice In Wonderland.
On April 25 Ms. Dich and Rizlaine carried out reconnaissance on various places in central London which could be locations for terrorist attacks.
The following day the pair bought three kitchen knives.
At 7pm on April 27 armed officers entered the house but Rizlaine was shot and injured during a scuffle.
Another woman, Khawla Barghouthi, 21, had also pleaded guilty to having information about acts of terrorism.
All four are expected to be sentenced on June 15.
"This investigation started with Safaa, and her attempts to travel out to Syria, marry a Daesh fighter and support their terrorist activity. Having been prevented from travelling to Syria, she then set about plotting an attack in the UK but her plans were being covered by the counter terrorism network and security services," said Deputy Assistant Commissioner Dean Haydon.
"After Safaa was arrested and charged, her mother and sister tried to pick up where she left off. But again, working with the security services, we tracked their plans and stopped them before they were able to put them into practice.
"All three women were filled with hate and toxic ideology and were determined to carry out a terrorist attack. Had they been successful, it could well have resulted in people being killed or seriously injured. But thanks to the work of the security services and counter terrorism police, their plans never came to fruition," added Mr. Haydon.
*Daesh (ISIL/ISIS/Islamic State), a terrorist group banned in Russia and an array of other countries.