The Kents are working royals. At this point neither of the York girls are expected to be working royals. Neither of them have attended the sort of event where tiaras are typically worn...and they didn't wear them to CHOGM either.
LaRae
The Michael's of Kent are not working royals but they do attend State Banquets.
Up to the 6th September, 2018 Beatrice and Eugenie have each done 7 official engagements, Prince Michael has done 6 and Princess Michael 7 (using my figures).
That is why I think the York girls will attend State Banquets as they are the sort of events that are included in the Michael of Kent's engagements:
This year
Prince Michael has been listed in the CC for the 1) Opening of CHOGM on the 19th April; 2) the Reception for VC and GC recipients on the 16th May; 3) Funeral for Patricia, Countess of Harewood (representing his sister Princess Alexandra) on the 18th May; 4) the Afternoon Party on the 5th June 5) Trooping the Colour on the 9th June; 6) Church Service for RAF on 11th July
This year
Princess Michael has been listed in the CC for the 1) Opening of CHOGM on the 19th April; 2) the Dinner for CHOGM on the 19th April; 3) the Queen's Birthday Concert on the 21st April; 4) the Reception for VC and GC recipients on the 16th May; 5) the Afternoon Party on the 5th June; 6) Trooping the Colour on the 9th June 7) Church Service for RAF on 11th July
This year
Princess Beatrice has been listed in the CC for the 1) fashion show on the 19th February (with Kate and Sophie); 2) the Dinner for CHOGM on the 19th April; 3) the Queen's Birthday Concert on the 21st April; 4) Chelsea Flower Show on the 21st May; 5) Reception for the Duke of Edinburgh Awards on 24th May; 6) Beating Retreat on the 7th June 7) Trooping the Colour on the 9th June
This year
Princess Eugenie has been listed in the CC for the 1) Dinner for CHOGM on the 19th April; 2) the Queen's Birthday Concert on the 21st April; 3) the Reception for VC and GC recipients on the 16th May; 4) Reception for the Duke of Edinburgh Awards on 24th May; 5) the Afternoon Party on the 31st May; 6) Beating Retreat on the 7th June; 7) Trooping the Colour on the 9th June
When we look at the events that Beatrice and Eugenie have attended this year, many of them are the same events that Prince and/or Princess Michael of Kent have attended:
CHOGM dinner, Afternoon Party at BP, Reception for VC and GC recipients, Trooping the Colour.