C# 自动映射并使用备用键

如何映射像这样的两个对象

 class Parent
{
    public Guid Id { get; set; }
    public IEnumerable<Child> Childrens { get; set; }
}

class Child
{
    public Guid Id { get; set; }
    public int AlternativeKey { get; set; }
}

父母2

{
    "Id": "00000000-0000-0000-0000-000000000000",
    "Children": [{
            "Id":"00000000-0000-0000-0000-000000000000",
            "AlternativeKey":"13",
            "Name":"ABC"
        },
        {
            "Id":"00000000-0000-0000-0000-000000000000",
            "AlternativeKey":"14",
            "Name":"Foo"
        }
        ]
}

现在我想把这些和automapper合并。结果应该是Parent1中Parent2的名称。我的问题是使用AlternativeKey作为映射主键，而不是Id

预期结果

{
    "Id": "1367debe-7d88-41c7-b152-0ff0747e5d4b",
    "Children": [{
            "Id":"8d1377b7-1190-48b1-aa21-53a2eb95837b",
            "AlternativeKey":"13",
            "Name":"ABC"
        },
        {
            "Id":"ed3eea42-4ff3-40f0-9b84-7f8c4ae6f603",
            "AlternativeKey":"14",
            "Name":"Foo"
        }
        ]
}

{
    "Id": "1367debe-7d88-41c7-b152-0ff0747e5d4b",
    "Children": [{
            "Id":"8d1377b7-1190-48b1-aa21-53a2eb95837b",
            "AlternativeKey":"13",
            "Name":"ABC"
        },
        {
            "Id":"ed3eea42-4ff3-40f0-9b84-7f8c4ae6f603",
            "AlternativeKey":"14",
            "Name":"Foo"
        }
        ]
}