The Duchess of Sussex's IRS tax review may end up exposing the Royal Family's wealth & the Royal Families riches. How can they avoid this?

Do they need to 'avoid' anything? Details of the wealth of members of the RF are a public record.

The tax records of the Duchess of Sussex are no longer of interest to the Internal Revenue Service of the United States, and she no longer files IRS tax returns. She is no longer a U.S. citizen. She gave up her U.S. citizenship and she is now a British citizen.

(She doesn't "earn" an income as Duchess ot Sussex that she would have to report to the IRS anyway).

No. Her personal assets have nothing to do with the Royal Family's assets.

And, the Royal Family's finances are public record--

https://www.royal.uk/royal-finances-0

Her Royal Highness doesn’t have derive personal income from what is paid to the Royal Family, her husband does and so it does not have to be declared.

If or when she becomes a naturalised citizen of The UK AND has disposed of all her assets based in The US, she will no longer have to declare future personal income to the IRS.

They will find a way, they always do, But it doesn't matter really, The fans of the monarchy will not believe anything bad against them.

get a life

her tac returns are controlled by very good accountants who will reveal nothing

She can give up her American citizenship.