You need to ask your question of professionals in these areas - I am not.

If you are looking to add to the disorders your son may have why not consider - if you did not get your son immediately after he was born - attachment disorder.   This disorder does, like Foetal alcohol syndrome, seem to stem from a definable set of circumstances in the very early life of the child.

However, will it really help you to add to his list of disorders?

You ask

"Could it be at possible that he has both syndromes at the same time"

diagnosis from the professionals suggest that this is possible as they will often link disorders sometimes with qualifying words like "mild".

Disorders vary but some, in my opinion, appear to be little more than a statement of behaviour characteristics that occur together in a significant number of individuals.   These either follow some kind of trauma (alcohol/attachment) or are considered to be inherited.   What links them are defined combinations of shared behaviour.   But what also links them is what is often missing from the diagnosis.   What is often missing is the professional understanding and help for parents to handle and/or train this behaviour once the diagnosis has been made.

If you look at my site ibi.org.uk you will find a similar number of behaviour characteristics that my clients children commonly display.   These are the children that I work successfully with on a daily basis.   This list of behaviours looks on the surface as serious as any list of behaviours associated with a behaviour disorder; yet although the children I work with may well have behaviour disorders these behaviours very definitely do not stem from a behaviour disorder.

My advice would be that you need to qualify your search for the correct "disorder".   You need to look not for the label but the detailed course of action that you need to apply to your son's behaviour once you have the correct label.   Why do you assume the one already given to you is not the correct one?   Could it be that it came with no plan of action no ideas about what you should do?   If, once you have correctly added another diagnosis to the current one, you also find practical advice is missing will it really help you?

You will still need to train your son to be able to cope with the rewards and sanctions that will be applied to his behaviour in the real world.

Whatever the diagnosis your job is easy to articulate - to prepare your son for the real world and modify his behaviour as much as is possible so that he can fit in and be happy in it.

If the professionals who give you the diagnosis also give you the practical means to help your son then, of course, follow it.   If however they do not then you will need to approach those who are skilled in training inappropriate behaviour, behaviour that does not have a label, since the constraints and punishments of the real world will be applied to your son whether he has a diagnosis or not.

For instance, even if your son as an adult has many of these serious syndromes and disorders the law of the land will be applied to his behaviour with absolutely no allowance being made whatsoever.   Surely this suggests that training needs to be applied to the behaviour associated with these "Disorders" now so he is prepared for this reality as early as possible.

I do not say this to have you curtail your search for the correct label just to make sure you determine from the outset the practical advantages and usefulness of each label once it is professionally applied to him.

The correct diagnosis is important, I hope nothing I have said has suggested otherwise, but once you have it, it should not be used, as it often is, to justify impotence and inaction.

I hope this helps.

Warwick