The Duke of Sussex, the Prince of Wales and the Duke of Cambridge have all been invited to attend the talks at the monarch’s Sandringham estate in Norfolk.
It will be the first meeting of the four since Prince Harry and Meghan Markle’s shock announcement on Wednesday that they will be stepping down as senior royals.
According to sources Charles will be travelling from Birkhall in Scotland, William from his Kensington Palace apartment while Harry from Frogmore Cottage near Windsor Castle.
They are expected to discuss a range of options and will try to come to an agreement before the meeting ends to stop the crisis causing lasting damage to the British monarchy.
Harry and Meghan are said to have left the Queen and senior royals ‘hurt’ after unexpectedly revealing their plans to become financially independent from the family and to spend more time in North America.
The monarch, Charles and William ordered their households on Thursday to work with the Sussexes’ team to quickly find a ‘workable solution’ to take a different path in life while still supporting Her Majesty.
Faced with speculation her son may leave the country to join his wife and son in Canada as early as next week, the Queen reportedly gave a 72 hour ultimatum for the pair’s future roles in the family to be finalised.
A royal source said: ‘The family will gather on Monday at Sandringham to talk things through, attended by Her Majesty, the Prince of Wales, the Duke of Cambridge and the Duke of Sussex.
‘Following a series of meetings and consultations across the last few days, there are a range of possibilities for the family to review which take into account the thinking the Sussexes outlined earlier in the week.
‘As we have said previously, making a change to the working life and role in the monarchy for the Duke and Duchess of Sussex requires complex and thoughtful discussions.
‘Next steps will be agreed at the meeting, the request for this to be resolved at pace is still her Majesty’s wish – the aim remains days not weeks.
‘There is genuine agreement and understanding that any decision will take time to be implemented.’
Meghan flew to Canada a few days ago where she spent a six-week festive break with Harry and baby son Archie in the province of British Columbia.
Ahead of the meeting, the royals will be given written proposals produced by their offices and others, including relevant government departments from the UK and Canada, where it is thought Harry and Meghan will establish a second home.
It is not known who else, if anyone, will be at the meeting – but it is likely the private secretaries of the four royals may join part of the talks to assist with any questions.
The atmosphere could be tense as the Sussexes’ announcement was made without consulting the Queen or any other senior royals on its content or timing.
Harry and Meghan’s declaration and the new official Sussexroyal.com website have thrown up important questions over funding for the couple’s round-the-clock security, media access to royal events.
And their desire for a half-way house, as both members of the monarchy and private individuals making a living, has been described as a ‘toxic mix’ by David McClure, an investigator into royal finances.
He said: ‘The history of senior royals making money – the two is a toxic mix. It hasn’t worked well in the past.
‘How can you be half-in, half-out – half the week perform public duties and the other half earn your own income with TV, lectures, books? It is fraught with dangers.’
He estimated Harry’s wealth as between £10-15 million, while he suggested former actress Meghan was worth £2-3 million.
The duke and duchess receive the majority of the funding for their public duties, and some of their private costs, from Charles – who pays the expenses out of the multimillion-pound income from his private Duchy of Cornwall estate.
But they wish to stop receiving money from the taxpayer – in the form of Sovereign Grant funds – so they can earn what their website describes as a ‘professional income’.
Other important issues to resolve include who will pay for the substantial security cost of protecting the couple and their baby son if they spend large portions of the year in Canada and possibly America.
The way to get started is to quit talking and begin doing.