Place egg whites in a large bowl; beat with a mixer at high speed until stiff peaks form. Combine sugar and water in a saucepan; bring to a boil. Cook, without stirring, until candy thermometer registers 238°. Pour hot sugar syrup in a thin stream over egg whites, beating at high speed until stiff peaks form.
Place 4 cups strawberries, lemon juice, and vanilla in a food processor or blender, and process for 1 minute or until smooth. Strain the strawberry mixture through a sieve over a large bowl; discard seeds. Gently stir one-fourth of egg white mixture into strawberry mixture; gently fold in the remaining egg white mixture.
Place 4 cups strawberries, marmalade, and liqueur in a food processor or blender; process for 1 minute or until smooth. Drizzle 1/2 cup sauce over egg white mixture; reserve remaining 1 1/2 cups sauce. Swirl sauce into egg white mixture using the tip of a knife. Cover; freeze until firm. Serve with remaining sauce and sliced berries.