Princes William and Harry will stand guard over the Queen's coffin in a vigil on Saturday while world leaders start arriving in the UK ahead of the funeral.
Mourners will continue to pay their respects during the day at Westminster Hall where the Queen lies in state with the queue getting close to 24 hours long from the start at Southwark Park.
Representatives from Commonwealth realms will also be invited to visit the coffin and world leaders arriving throughout the weekend will be able to sign a book of condolence at Lancaster House.
And a vigil will be held by the Queen's eight grandchildren with the Prince Prince of Wales at the head and the Duke of Sussex at the foot.
William will be flanked by his cousins Zara Tindall and Peter Philips, the children of the Princess Royal; while Harry will be with the Duke of York's daughters Princesses Beatrice and Eugenie.
The Earl of Wessex's children Lady Louise and Viscount Severn will stand near the middle.
It follows the Queen's children holding an emotional vigil on Friday night.
And Harry, who saw action on the front line during two tours of duty in Afghanistan, will join his brother William in wearing uniform.
He has previously been denied the chance to wear his military uniform as he publicly mourns, because he is no longer a working royal.
Now royal sources say the King has decided his youngest son can wear uniform for the vigil.
Despite being a former Army officer, he has been in civilian dress for official events, including walking behind his grandmother's coffin on Wednesday when it was carried to Westminster Hall for lying in state.
With world leaders and dignitaries arriving on Saturday, Liz Truss will meet the prime ministers of Australia and New Zealand - Anthony Albanese and Jacinda Ardern - at the Government's Chevening country residence, a No 10 spokesperson said.
Charles concluded his tour of the home nations on Friday, starting his day with a visit to Wales, after trips to Northern Ireland and Scotland in recent days.
He will meet chiefs of staff at Buckingham Palace on Saturday and visit police headquarters to thank the emergency services for their work in planning the funeral.
Then the King and Queen Consort will also attend a lunch for governors general, and meet Realm prime ministers at Buckingham Palace.
Two thousand people will gather inside Westminster Abbey in London on Monday for the Queen's funeral.
Some 800 people, including members of the Queen's Household and Windsor estate staff, will attend the committal service afterwards at 4pm in St George's Chapel, Windsor Castle.
After the funeral, the King and members of the royal family will walk behind the Queen's coffin to Wellington Arch when it leaves Westminster Abbey, before it is driven to Windsor on the state hearse.
The Mirror has contacted Buckingham Palace for comment.
