Put wine, bouquet garni & mussels in a large saucepan.  Cover & steam until the mussels open.  Discard mussels that do not open.

Strain & reserve wine & mussel liquor.

Put aside 6 of the cooked mussels, still in shells, to use as a garnish.  Remove mussel meats from the other 9 mussels.  Finely chop or mince 3 mussel meats.  Roughly chop the remaining 6 mussel meats.

Melt butter in the same saucepan.  Add chopped onion & cook until translucent.

Blend in flour & cook until frothy, then add minced mussel meats.

Measure wine & mussel liquor & add sufficient fish stock to make up 3½ cups liquid.  Gradually stir this liquid & the milk into onion mixture 1 cup at a time, boiling between each addition.

Mix in cream, chopped mussels & oysters.  Heat gently until the oysters are cooked.  Add the 6 reserved opened mussels, still in shells, to soup.  Heat through but do not boil.  Season to taste with salt & pepper.

Serve in large soup bowl with an opened mussel in each bowl.