I want to suggest that the Sims should be able to have twins and triplets and there should be a special place where wedding ceremonies are conducted with a wedding officiant.
It would be fun to have twins etc.! As for the wedding venue, there IS! During the Wedding Belles event, a few updates back, you could earn a wedding house lot where you could get your engaged sims married,and have another sim officiate! I believe there is also a wedding venue location on the tropical romance island.