Just as a point of interest/curiosity, you can book a round-trip Riga-AMS-DUB on the KLM (Lithuania) website. It costs around LTL 1,400 (whatever that is) and the flights are operated by Air Baltic and Aer Lingus. You'll probably end up on the exact same flights but with the 'security' of having a through (connecting) ticket that KLM would have to honour in case of missed connexion.
-- Henry