Liomsa - mine, leatsa - yours, linne - ours. How would I say "theirs" and "yours" plural?
Is leosan é = It is theirs
Is libhse é = It is yours
You're a legend! Go raibh maith agat!
you are the father!
Why does "Is linne iad na buachaillí" not work?
is :- "Is linne iad na buachaillí" wrong?
That iad serves no purpose in this construction. It's just Is linne na buachaillí.
I used "Tá" instead of "Is", how is that wrong?
Is le is a colloquial structure for ownership. Tá le makes no sense.
What about tá ... againn?
That's expresses possession. Not quite the same thing.
Why is "buachailli" not eclipsed?
Because there's no preposition + definite noun for the boys. The preposition part is part of what expresses ownership. Also, it's never lenited with the plural definite article.