Actually, do you know if article 17 applies in cases where nationality is acquired via parentage? I can see how it mightn't and only in cases where grand-parentage entitles a conferral of citizenship.
The
Citizen Information website contains the following information:
It appears, then, that nationality is conferred automatically from birth to all those persons born to Irish nationals. However, to acquire Irish nationality through grand-parentage, it appears that the applicant has to apply to be included in the foreign births register and they're deemed to be an Irish national from the date of acquisition.