AutoMapper -- One-to-many mapping of tree - automapper

Question

I have the following classes:
public class OneToManySource {
public OneToManySource SourceChild { get;set; } // will sometimes be null
public int Value { get; set; }
}
public interface IDestination
{
}
public class ChildlessDestination: IDestination
{
public int DestValue { get; set; }
}
public class ChildedDestination: IDestination
{
public int DestValue { get; set; }
public IDestination DestinationChild { get; set; } // Never null. If it would be null, use a ChildlessDestination instead.
}
I want to map these back and forth in the sensible way. If a source has a child, it goes to a ChildedDestination. Otherwise, it goes to a ChildlessDestination.
I have the following, which works, but it's ugly. I'm wondering if it can be cleaned up. In particular, the "ConstructUsing" gets the job done, but it also seems to be (understandably) opaque to AutoMapper's internal smarts. So ReverseMap() there doesn't work. Instead of that, we are stuck with two other ReverseMap() calls, and also the last CreateMap().
For example, would I be better off starting with the reverse map?
public MapperConfigurationExpression Configure(MapperConfigurationExpression expression) {
expression.CreateMap<OneToManySource, ChildedDestination>()
.ForMember(d => d.DestValue, cfg => cfg.MapFrom(s => s.Value))
.ForMember(d => d.DestinationChild, opt => opt.MapFrom(s => s.SourceChild))
.ReverseMap();
expression.CreateMap<OneToManySource, ChildlessDestination>()
.ForMember(d => d.DestValue, cfg => cfg.MapFrom(s => s.Value))
.ReverseMap();
expression.CreateMap<OneToManySource, IDestination>()
.ConstructUsing((source, context) =>
{
if (source.SourceChild == null) {
return context.Mapper.Map<ChildlessDestination>(source);
}
return context.Mapper.Map<ChildedDestination>(source);
});
expression.CreateMap<IDestination, OneToManySource>()
.ConstructUsing((source, context) =>
{
return context.Mapper.Map<OneToManySource>(source);
});
return expression;
}