‌So the latest information is that even though Prince Harry and Meghan Markle have declared that they will travel to the U.K. for the Queen's Platinum Jubilee celebrations next month, the couple has been excluded from the balcony appearance lineup because they are not working members of the royal family anymore.
‌Queen has decided to reduce the number of royal family members in the Buckingham palace for trooping the colours ceremony this year. Buckingham Palace said that the move to only include working royals was made ‘after careful consideration. What does working royal stand for! A working royal is a member of the royal family who represents the Queen at official engagements.

In representing the Queen, a working royal will often perform any duties as needed including:
• Meeting with international dignitaries
• Hosting official state dinners and other events
• Attending parliamentary and constitutional functions
• Handing out honours
• Carrying out international trips and tours
• Opening buildings

This is purely done on the queen's behalf. Because being a working royal is considered a full-time job, living costs, accommodation, and any expenses are not covered by the appropriate government department but are covered by the Queen.

The seniority of that working royal will be intervened between the various government bodies, Buckingham Palace, ambassadors, or high commissioners in the overseas country to ensure that the person is of appropriate standing to achieve the task at hand.

The current working royals include

The Queen

The Prince of Wales, Prince Charles- Charles is said to be on ‘stand by to represent the Queen at the opening of Parliament later this month.

The Duchess of Cornwall, Camilla- The Queen confirmed this year that Camilla will be Queen Consort when Prince Charles ascends to the throne.

The Duke and Duchess of Cambridge, Prince William and Kate Middleton

Anne, the Princess Royal

The Earl and Countess of Wessex, Prince Edward and Sophie

The Duke and Duchess of Gloucester, Prince Richard and Birgitte.