Carefully pour the bottle of Rosé in a zip lock bag. Zip and store flat in the freezer.
In a large container, such as a quart mason jar or mixing bowl, combine the lemon juice, sugar, and warm water. Water should be warm enough to melt the sugar but not boiling.
Add elderflower liquor to the lemonade mix. Zip and store flat in the freezer.
Allow to freeze at least six hours, overnight is best.
In a pitcher or punch bowl, empty both zip lock bags. Use a wooden spoon to stir and remove any clumps from the lemonade mixture.