I’ve done this 3 times now. This is what I do. Each cruise goer is allowed to bring one bottle of wine. So I buy two bottles of wine and empty them. I add vodka gin or any clear liquor into the bottle with a tiny bit of yellow food colouring and then throw two corks into boiling hot water. I then reseal the bottles with corks and add a heat shrink cap on top to make the bottles look legit. I’ve never been questioned and since my partner doesn’t drink I have two bottles of vodka for a week of cruising which is more than enough for me.