The Covent Garden Soup people did a recipe book a few years ago called "Soup for All Seasons" and they had one called "Turkey and all the Trimmings" - it used Christmas Day leftovers to make a tasty smooth soup. You could make a portion or two of it from what you are already doing for the rest of your guests; that would save time and feel more inclusive. Here is the original recipe (the quantities shown make enough for 4):
850ml (30fl oz) turkey stock 100g (3½ oz) cooked turkey meat
2 small carrots, diced Half a small swede, diced
2 small parsnips, diced 1 small onion, diced
1 tablespoon fresh thyme, chopped 2 tablespoons olive oil
1 tablespoon fresh parsley, chopped
TRIMMINGS: 8 stuffing balls 8 chipolatas wrapped in bacon
Heat the oil in a saucepan then sweat all the vegetables for 10 minutes without browning. Add the thyme and stock then cover and simmer for 20 minutes. Add the turkey and cook for a further 10 minutes.
Meanwhile, reheat the stuffing balls and the chipolatas wrapped in bacon until they are piping hot.
Blend the soup then reheat gently, adding the parsley and seasoning to taste. Pour the soup into bowls and serve with the trimmings on top.
The idea was that you float the stuffing balls and pigs-in-blankets in the soup like festive croutons - but you could always blend them with the soup or leave them out.
There's a modified online version here:
Christmas Dinner Soup - Modified Recipe - Recipezazz.com
Hope this helps.