@dotGiff Gimli was travelling with Gloin to warn Bilbo of Mordor emissaries looking for a halfling named Baggins. Legolas was there to deliver the bad news that Gollum escaped. Boromir was there because he and his brother were having dreams about the sword that was broken in Imladris.
@dotGiff Speaking of Elrond, he never called the Council, why wouldn't Theoden or King Brand be invited? Everyone was there by chance, not chance when God (Eru Iluvitar) destined all those people to be in Imladris at the same time "by chance."