I won't pretend to know all the ins and outs of laws in different countries, so I'll just ask the question - in the US, for example, are there any caveats to this law?
Here in the UK, the legal age is 18, but that's only to buy alcohol and to drink on most licensed premises. Under the law, you can have alcohol at home if you're over 5(!) and the key one is that you can have beer, wine, or cider with a meal at a restaurant from age 16. If there's a part of the law like that last scenario, even if she were "under age" Layla would be old enough to be allowed wine in that dinner scenario.