Last year there were 245 applications for 180 places at the 1,100-pupil school. New physical education, science and information and communications technology facilities have been added over the past three years, plus a new dining area and library.
In 2000 the Qureshis, who live in one of the terraces yards from the school, appealed three times without success to get their 16-year-old son Shiraz into Laisterdyke. Instead, he had to go to Carlton Bolling college, one and a half miles from his home.
Zarina Qureshi, 40, Shiraz's mother, said: "I wanted Shiraz to go to Laisterdyke but because he had no siblings there, he did not get in."
She supports getting rid of the sibling rule.
"If siblings are together they can hook up and misbehave," she said.
Mrs Qureshi's 12-year-old son Sameer starts at Laisterdyke in September.
Sameer's older brother Islam, 22, said: "He was lucky this year."
Ansar Parveen, 42, and her husband Ghulam Shabir, 46, also from Pakistan, have three children at Laisterdyke including Umar, 14.
Umar, who starts Year 10 in September, understands why the school wanted to abolish the sibling rule: "Some children at the school ask 'what is the point?'.
"They know if their parents do not say anything to the bigger brother they can get away with it too. It is a big problem at the school."
Ms Parveen and Mr Shabir agree with the adjudicator's decision. Ms Parveen said: "I like that they go to the same school. If one child does something wrong the other will tell me. There are no secrets."
Mr Shabir said: "If they did not go to Laisterdyke they would have to go to Carlton Bolling or Tong school and it is too far, and then they tell us not to use the car because it is healthier to walk."