Labhrás wrote:
Errigal wrote:
They won't be familiar with that way of expressing the superlative though, so, using the relative of the copula: Aimsigh duine arb é/í an duine is óige sa teaghlach (é/í). I don't think the final é/í is necessary.
This sentence feels wrong.
ar(b) is an indirect relative, (first) duine is subject and antecedent of the relative clause ...
So, a direct relative* is necessary (... is ...),
I don't think a resumptive pronoun (final é/í) is possible here at all. (But it would be necessary for an indirect relative)
Yes, I can tell a direct relative from an indirect - rocket science it ain't

- and I know that it's a direct relative in this case. However, it seems the indirect structure is used in identification sentences whether the relative is direct or indirect. Not that I've seen this in any grammar book - just my (admittedly limited) experience.
Labhrás, google "arb(h) é/í an" and "arb(h) iad na" and you'll see. Many of them are genuine indirect relatives of course - genitives and occasional datives - but at least as many are technically direct relatives.
Labhrás wrote:
But ...
Aimsigh an duine is é an duine is óige sa teaghlach
doesn't feel any better

(too complicated, as well as my own suggestion above (... an té atá ar an duine ...)
Not only does it not feel any better. It's just wrong.
Labhrás wrote:
Simplified and sufficient:
Aimsigh an duine is óige sa teaghlach
But this isn't at all what MsHollywood is looking for and is no use to him/her. Read the original request again.
Actually, I'd been wondering if my version could be shortened to
Aimsigh duine arb é is óige sa teaghlach and then I came upon this in a 'Tráth na gCeist' book based on a quiz competition on RnaG:
Cé a bhain rás 100m breaststroke ag na cluichí Ollimpeacha i 1988 agus arb é is gaiste sa domhan a bhfuii an fad sin snáfa aige?