How fancy or not do they want to be?
There's a million different scenarios. We once saw a lovely private cocktail party being held at the Wilderness Lodge in the ground floor rooms along the main pool. They had tables with hors d'ourvres and cocktails set up on the grass sort alongside the left side of the pool, but behind hedges that were there so there was some privacy. The people who were attending the party were staying in those rooms right there, so everyone was kind of mingling between the rooms and enjoying the cocktails and so on. It looked quite lovely.
You can make a dining reservation for 10 at any of the restaurants. You don't get into group dining until you have a party of 13 or more.
If they want to be a little fancier, how about getting married at the beach at the Contemporary and then to the California Grill for dinner? I think there is a sort of separated room near the back of that restaurant that could be nice.
If they will be staying at the BCV, they could get married on the beach there, and then do cocktails/hors d'ouervres back in their room or poolside at the quiet pool. They could probably actually do the whole thing poolside if they didn't want to go from the beach back to the pool.
The bigger problem if they don't want to involve Disney will be to get someone to marry them. They'll need to find out the rules and regs for getting married in Florida(if they don't live there) and find an officiant. I don;t know how they'd go about doing that if they are not familair with the area.