The mesader kidushin (organizer of the wedding ceremony) makes sure that all procedures are done properly. He says the blessing on the cup of wine and fulfills that requirement for both the bride and groom. He says the second blessing and fulfills it for the groom. In both cases, the bride and groom must have the intention that the mesader kidushin is saying those blessings on their behalf. The groom and bride drink some of the wine.