Buckingham Palace sources said the Queen, her son and two grandsons will have been presented with a range of draft written proposals - compiled by a team of aides and private secretaries - ahead of the crunch meeting.
The Duchess of Sussex is expected to dial into the talks from Canada, having flown back to the country on Thursday evening to be reunited with eight-month-old son Archie.
Prince Charles has cut short his visit to Scotland and traveled to Sandringham to help put an end to the crisis engulfing the family. The Queen traditionally remains at Sandringham, her Norfolk estate, after Christmas until Feb 6, the anniversary of the death of her father, King George VI.
Aides stressed it was a "family discussion" that all four royal households hoped would go some way to reaching a solution to the current impasse.
A palace source said: "The family will gather on Monday at Sandringham to talk things through. The Queen, the Prince of Wales, the Duke of Cambridge and the Duke of Sussex will meet for the first time.
"There are a range of possibilities for the family to review which take into account the thinking the Sussexes outlined earlier in the week."
The aide stressed that striking a deal would not be simple.
"Making a change to the working life and role in the monarchy for the Duke and Duchess of Sussex requires complex and thoughtful discussion," they added.
"Next steps will be agreed at the meeting and the request for this to be resolved at pace is still Her Majesty's wish. The aim remains for this to be in days, not weeks. There is genuine agreement and understanding that any decision will take time to be implemented."
Aides will be hoping the Sussexes' "red lines" will be made clear at the meeting so discussions can progress.
It is hoped that when a deal is finally agreed it will form a blueprint for future royal generations, including Princess Charlotte and Prince Louis.
A source close to the Sussexes said: "They have been talking about the principle for some time. A lot of people might have been surprised by the speed, but the principle has been on everyone's radar for some time.
"They are looking for a swift resolution and clarity for everyone's sake."
Aides confirmed Prince Harry has further engagements in the coming weeks, scotching claims he may be planning to fly to Canada in the next few days with no intention of returning.