Ids.cs

static void Main(string[] args)
{
	var config = new MapperConfiguration(cfg =>
	{
		cfg.CreateMap<A, ADto>().ForMember(_ => _.ListOfB, _ => _.UseDestinationValue());
		cfg.CreateMap<B, BDto>();
		cfg.CreateMap<B1, B1Dto>().IncludeBase<B, BDto>();
	});
	config.AssertConfigurationIsValid();
	var mapper = config.CreateMapper();
	
	var source_a = new A();
	var b = new B();
	var b1 = new B1();
	
	source_a.ListOfB.AddRange(new B[] { b, b, b1, b1 });
	
	var target_a = mapper.Map<ADto>(source_a).Dump();
}

class A { public List<B> ListOfB = new List<B>(); }
class B
{
    public Guid Id = Guid.NewGuid();
}
class B1 : B { }

class ADto { public List<BDto> ListOfB = new List<BDto>(); }
class BDto
{
    public Guid Id = Guid.NewGuid();
}
class B1Dto : BDto { }