An exhibition celebrating the life and legacy of the murdered MP Jo Cox opens in Manchester this week, with contributions from her children. Eight-year-old Lejla and her brother, Cuillin, 10, have provided captions for the show at the People’s History Museum (PHM), Britain’s national museum of democracy. They explain how they helped to design the Jo Cox coat of arms, installed in parliament after she was killed in June 2016. She was murdered by a far-right terrorist before the Brexit referendum in her West Yorkshire constituency of Batley and Spen. “This is the coat of arms of Jo Cox (our mum),” reads the caption on a display case showing the ornate certificate produced to certify the heraldic shields which are produced for all MPs killed in office. “Daddy and the two of us designed it. It has the three suffragette colours of green, white and violet, in the middle is a mountain and the green and blue represent rivers and hills.” The rivers are the Thames, where they lived on a houseboat; the Wye, where they holidayed; and the Swale in Yorkshire, where Cox was born. “The red rose stands for the Labour party and the white rose stands for Yorkshire. There are four roses because there are four of us. It means a lot to us because it is handwritten and because it shows things Mummy cared about,” the children write. Central to the exhibition is the Jo Cox memorial wall, on public display for the first time since her murder, when it was erected outside the Houses of Parliament. Now part of PHM’s permanent collection, the wall features the handwritten tributes of hundreds of people, including children, expressing their horror at her death. “Love will prevail – one day soon?” wrote one mourner, in hope as much as expectation. It stands alongside a virtual wall of hope on which visitors to the museum and online can add their personal tributes. Also on display for the first time are the placards, banners and artworks that were created in the aftermath of Cox’s murder. Her family have loaned a Peruvian-style woolly hat that she would wear on their walking trips, particularly munrobagging in Scotland. Now, when they scale a new peak they take the hat with them in her memory and photograph it at the summit. Much of the More in Common exhibition is curated by new Mancunians, who used Cox’s legacy to explore their own histories of migration. It has been funded by the EU and should have opened last year for the fourth anniversary of Cox’s death. “We are part of a European project which is more broadly around migration stories, but our bit of it was always going to be looking the UK’s exit from the EU and what that meant to people who weren’t UK nationals,” said Katy Ashton, PHM’s director. It is part of a series of PHM exhibits looking at migration in the UK. Another, which also opens on Wednesday, looks at the history of the “hostile environment” for immigrants, featuring Daily Express front pages and testimony from people detained in immigration removal centres. There is also an exhibition exploring the often miserable lives of the 19,000 domestic workers brought to the UK as maids, chauffeurs and nannies each year. Cox’s sister, Kim Leadbeater, said last week that she hoped to follow in Cox’s footsteps as MP for Batley and Spen. A byelection will be held this summer after Cox’s successor, Tracy Brabin, was elected as the first mayor of West Yorkshire.