Prepare 1-quart souffle dish with lightly oiled 1-inch waxed paper collar.
Set aside.
Combine Grand Marnier and lemon juice in small bowl.
Sprinkle gelatin over top and let stand until softened.
Combine egg yolks, 3/4 cup sugar, orange juice, marmalade and salt in top of double boiler.
Set over simmering water and cook, whisking constantly until mixture thickens and coats spoon, about 5 minutes.
Remove from heat.
Stir in softened gelatin and lemon peel.
Turn into large bowl.
Let custard cool to room temperature.
Beat egg whites until foamy.
Gradually add remaining 1/4 cup sugar and continue beating until stiff peaks form.
In another bowl, whip 1 cup cream until soft peaks form.
Stir some of whites into cooled custard to lighten, then fold in remaining whites, blending well.
Fold in whipped cream.
Turn into prepared dish.
Refrigerate until souffle is firm and spongy.
For garnish: Whip remaining cream with powdered sugar until stiff.
Spoon into pastry bag fitted with star tip.
Pipe rosettes over top of souffle.
Decorate with orange segments.