Originally Posted by MsJulie
Princess Beatrice has a coat of arms. In looking on the net it does not appear to have changed at all since her marriage.
Originally Posted by AC21091968
According to Wikipedia and quick Google search, Princess Eugenie's coat of arms has not changed since marriage.
Posters on Wikipedia and other websites are just guessing like the rest of us.
For those who have an interest in this question, please review the laws of married women's arms from the heraldic authority of England and Wales. I've written a short summary below.
The Arms of Women, a Decree. | The Heraldry Society
Same-sex marriages - College of Arms
The Law of Arms - College of Arms
With the laws of arms in England and Wales, a woman who bears a coat of arms through her father or by grant to herself, and whose husband likewise bears a coat of arms through his father or by grant to himself, has three options available to her.
She may bear her paternal or granted arms alone.
She may bear her husband's paternal or granted arms alone.
Or she may marshal, i.e. unite, the two coats of arms. Usually they would be be marshalled by impalement (placing the two coats side by side on the same shield), however, where the wife is a grantee or "heraldic heiress" her arms are usually placed on an inescutcheon (smaller shield) at the center of her husband's arms.
Her husband is entitled to choose between bearing his paternal/granted arms alone or marshalling the two coats, though from what I hear the vast majority of men prefer to bear their own arms alone.
That being said, I have no information about how an Italian coat of arms belonging to a British citizen would be dealt with by the British or Italian laws of arms.
Like the posters on Wikipedia etc., my guess would be that Princesses Beatrice and Eugenie and the other married blood princesses prefer to bear their own arms alone, as eminent women often do. But unless they have verifiably stated their preferences, it is only an educated guess.
Originally Posted by Countessmeout
Coat of arms are passed through the father's line not the mother's line.
It depends on what one means by "passed through the father's line not the mother's line.". The English law provides that the general right to use arms is only transmissible through fathers, but a child who bears his or her father's arms may quarter them with the arms of their mother if the mother is a heraldic heiress or grantee (refer to the above links for sources).