The Duke of Cambridge will take the lead on the military elements, reviewing Trooping the Colour in a formal inspection a week before the Queen carries out her review as one of the centrepieces of the Jubilee weekend.
The Duchess of Cambridge will continue her focus on children and the outside world with Superbloom: the Tower of London project to flood the moat with flowers, complete with a slide.
Prince George, eight, Princess Charlotte, who will soon be seven, and four-year-old Prince Louis will take part in events, although their parents are likely to follow the pattern they set for the Duke of Edinburgh's service of thanksgiving in confirming their attendance only at the last minute.
The trio have previously joined the Duchess at her "back to nature" garden in the Chelsea Flower Show, and could make a similar appearance for the Superbloom project.
They will appear on the Buckingham Palace balcony, and fans hope to see them make their debut in the carriages to Trooping the Colour. Their father Prince William took his first formal carriage ride at the age of four.
Detailed plans for the Royal Family's attendance over the Jubilee weekend are still being drawn up.
The Duke of Sussex is said to remain genuinely undecided about whether he, the Duchess and their two children will fly to London for the event to mark the Queen's 70 years on the throne.
They will receive security for all Jubilee events, the Sunday Telegraph has established, removing one of the key obstacles.
The Duke, who is suing the Home Office over his security arrangements, has previously said it would not be safe for his family to be in the UK. He and the Duchess last week visited the Queen at Windsor Castle without harm.
A palace source said the ball was in his court, with his grandmother and father keen to welcome the Sussexes to "family" events.
Prince Harry and Meghan will be unable to attend formal working elements of the Jubilee, having left their official roles when they moved to California two years ago.
Asked in a recent US television interview whether he planned to attend, the Duke said: "I don't know."
The approach has exasperated some at the palace, with less than six weeks to go until the Jubilee bank holiday weekend begins and plans being finalised.
The Duke, who has been in Europe for the Invictus Games, has spoken freely about his visit to see the Queen and their "special" bond during an interview with an American breakfast chat show.
Some at the palace also harbour fears that the Duke of York, who recently paid a multi-million-pound settlement for a sex abuse civil case in the US, will not bow out of the Jubilee as previously indicated.
It is now thought he may try to appear at "family" events, after being at the side of the Queen for the thanksgiving service for his father at Westminster Abbey.
Other members of the family, including the Princess Royal and the Wessexes, will make appearances throughout the Jubilee weekend.
The millennial royal cousins - Peter Phillips and Zara Tindall, Princess Beatrice and Princess Eugenie and the Cambridges, are expected to lead the fun at the concert.
The Queen, who will not be able to attend the number of public engagements as she has managed in previous jubilees thanks to mobility problems, will focus on being well enough for key moments including the Epson Derby and Trooping, where she could use a car to travel if the carriage proved too uncomfortable.
The Platinum Jubilee will run from June 2 to 5, with beacons being lit, street parties thrown, and an all-singing, all-dancing pageant down the Mall.
