Redwolf wrote:
Yes...that's what I was thinking of. I know a couple of Irish speakers (both males) here with double first names, and I've been curious as to how to address them.
Choose one of the two names and vocativise that.
Or ask them how they would address themselves in Irish, if they’re native speakers.
Typologically speaking, it would be most likely, if their names are considered a single name, to lenite the first of the two names, but only put the second one in the vocative:
a Sheán-Mícheáil. If the two names are considered separate first names, however, having both lenited and in the vocative would make sense (at least historically and ideally speaking):
a Sheáin Mhícheáil.
Considering how rare double-barelled names are traditionally in Irish, though, I think you can pretty much get away with anything.