Just Smile –
In New York State, as a matter of law a parent can provide permission to his minor child to consume any amount (there is no prescribed limit in the law) of alcohol in generally any place, with some limited exclusions such as within a motor vehicle. And for any reason, not just religious. Nor are there any legal restrictions on the BAC for a minor who is not operating a motor vehicle. And they do not have to pour the drink.
Obviously, a parent is legally responsible for their safety of their child, whether their child is drinking an unreasonable amount of alcohol or engaging in any other unsafe activity. But that is not specific to alcohol consumption.
See the link on the bottom of the previous page of this thread, to the National Institutes of Health, describing each State’s minor alcohol laws.