The Law Is Clear:

According to North Carolina General Statute (NCSG) 18B-302 (a), as a parent/guardian, you cannot legally give alcohol to any child, including your own, who is under the age of 21, even in your own residence, even with another parent’s permission, no matter what the circumstance.  In addition, NCGS 14-316.1; 18B-302(c) specifies that you can not knowingly allow an underage person to consume or possess alcohol in your residence, even if you did not provide the alcohol.