I've found a few newspaper articles for the wedding, each a little different (one mentions ferns in the bouquet and lillies but no roses!) but essentially the same. I have also found the following articles for the other sisters but sadly no pics of the grooms for comparison:
GERALINE - [the dress] a lovely diesis of white crepe, the swathed bodice draped with beautiful old Carickmacross lace, which fell over the front of the skirt in graceful folds. The long court train falling from the shoulders was entirely composed of the same priceless lace, over softest chiffon. A lace veil (originally worn by the bride's mother) was arranged over high coronet of orange blossoms. Her ornaments consisted of a pearl necklace and diamond pendant. She carried a beautiful bouquet of white roses and stephanotis.
MARAGARET - She wore a beautiful dress of rich, ivory duchesse satin, the skirt and corsage being handsomely embroidered with fine silver paulettes and diamonds in Louis XV bows. The [corsage?] had a yoke of tucked chiffon trimmed with lace and orange blossoms, while the collar and long transparent sleeves, as well as the veil, were of beautiful old Carrickmacross lace. The long Court train falling from the shoulders was draped on the left side with white chiffon, finishing off with true lover's knot and a spray of orange blossoms. Her ornaments consisted of a diamond pendant and a pearl and diamond brooch. She carried a goodyear bouquet from the bridegroom, composed of roses, lilies of the valley, stephanotes, tuberoses, etc.