If you want your sims to have a wedding at home with all the family watching but you don’t want to throw a wedding party, just use one of the wedding arches available in buy mode. It’s just a step up from the “have private wedding” personal interaction; it gets the sims to exchange vows but involves the household too. Use the “get married” interaction on the arch and the couple will, assuming their relationship score is high enough, use the arch as the location to exchange rings. Plus everyone in the house at the time they do this will come over to the arch to watch it happen.
In my sim’s case, there was only the butler in the house besides the happy couple, but he stopped his butling (going so far as to drop a pile of garbage on the kitchen floor instead of putting it in the trash compactor) to watch the event too.