using System;

public class Program

{

    public record ParentRecord(Guid Id, string Value);

​

    public record ChildRecord(Guid Id, string Value, string Extra) : ParentRecord(Id, Value); 

    public static void Main()

    {

        var childRecord = new ChildRecord(Guid.NewGuid(), "child", "extra");

        Console.WriteLine(childRecord);

        ParentRecord parentRecord = new ParentRecord(Guid.NewGuid(), "parent");

        Console.WriteLine(parentRecord);

        parentRecord = childRecord;

        Console.WriteLine(parentRecord);

    }

}