Maybe she can attend these events.But never see The Princess Royal or The Countess of Wessex or the Gloucesters,Kents curtsey to her!
Far as I know, as the wife of the Prince of Wales and an HRH, she becomes the second lady in the land. Officially that means the other royal ladies (apart from the Queen) would have to curtsey to her, but I don't think the royal family tends to be so formal, apart from curtseying to the Queen at official functions (not sure about private ones).