Shamis went to Penn undergrad with Nyssa, Tom's sister. She introduced them many moons later. (That is enough information to post on the inter-web. If you do not know the rest of the story, ask during the wedding weekend.)
Tom's parents got married on 4/11. Shamis and Tom got engaged on 4/11. Tom likes symbolism so the ceremony will start precisely at 4:11PM. Don't be late!