Lets face it - Bari was a real 'melting pot' for units having an interest in Balkans, Yugoslavia etc. I am sure I have read of US interests in the theatre too, supported by your findings regarding OSS (Special Bari Section).
This article is lengthy but interesting and worthy of further analysis:
http://www.britain-at-war.org.uk/ww2...driatic_hq.htm
Note the LFA formation sign in the MT HQ image. Is the bloke front second left a Yank?
I have a feeling the following (next) article makes the common mistake of misappropriating the acronym 'SBS', - and it is Jellicoe's 'Special Boat Squadron' that is being referred to when the author talks of the unit under LFA (as opposed to earlier Commando 'Special Boat Section' briefly incorporated into early SAS. The (Royal Marine associated) 'Special Boat Service' is a more recent reincarnation.
https://jramc.bmj.com/content/jramc/85/1/41.full.pdf
There is the whole matter of the role and composition of Brigadier Turnbull's Raiding Forces Middle East - it is all a fascinating but complex theatre of war to analyse.
I hope the articles are of interest
Having not seen the discussion on the American forum it is difficult to comment more specifically.
Regards
Mike