two of my daughters started to use the Irish form of their surname years ago. They both have non-Irish Christian names, so left them alone.
they just applied for their next driving licence using their “irish” surname, and also for their next passport.
No problem, even when processing USA Green Cards.
(I suppose … born and living in Ireland at the time, it was easier than if living abroad.
Then, by the time they were applying for jobs etc, all their documentation was in the Irish form.
(I mostly use the English version of my name, but not with my Irish-speaking friends)
beir bua – eadaoin