MapIntoDestination

public static void Main()
{
	Mapper.Initialize(a => a.AddProfile<TestProfile>());

	var mapSource = new SourceTestModel { SourceDetailTestProperty = 5, SourceBaseTestProperty = 10, UseFirstModel = true };
	var expectedResult = new FirstTargetTestModel { DetailTestProperty = 5, BaseTestProperty = 10 };
	
	Mapper.Map<ITestDetail>(mapSource).Dump();
}

public class SourceTestModel
{
   public int SourceDetailTestProperty { get; set; }

   public int SourceBaseTestProperty { get; set; }

   public bool UseFirstModel { get; set; }
}

public class FirstTargetTestModel : ITestDetail, ITestBase
{
   public int DetailTestProperty { get; set; }

   public int BaseTestProperty { get; set; }
}

public class SecondTargetTestModel : ITestDetail, ITestBase
{
   public int DetailTestProperty { get; set; }

   public int BaseTestProperty { get; set; }
}

public interface ITest { }

public interface ITestBase
{
   int BaseTestProperty { get; set; }
}

public interface ITestDetail : ITest
{
   int DetailTestProperty { get; set; }
}

public class TestProfile : Profile
{
   public TestProfile()
   {
		RecognizePrefixes("Source");
		CreateMap<SourceTestModel, FirstTargetTestModel>();
		CreateMap<SourceTestModel, SecondTargetTestModel>();
		
		CreateMap<SourceTestModel, ITestDetail>()
			.ConvertUsing(a => 
			{
				var destination = a.UseFirstModel ? new FirstTargetTestModel() as ITestDetail : new SecondTargetTestModel() as ITestDetail;
				Mapper.Map(a, destination);
				return destination;
			});
	}
}