Child Support Query - Bit complicated!

CJB2012

Hi there, trying to help my ex a little as he's in a bit of a predicament!
He has our two children which he contributes to informally, and has two children which live in in Trinidad which he pays to their mother monthly and sends money religiously via Western Union.
Unfortunately, for him - he had a bit of a bad relationship last year and his ex girlfriend has had a baby.  Whilst he doesn't mind paying maintannce for this baby - she has decided to contact Child Support to do so formally.
He called this morning, and gave details - details of the new baby, my two children - and he was trying to tell them about his two girls who live abroad that he supports but the man stated they couldn't be taken into account as no court order (very difficult to do in the Carribean) 
Is there anything he can do to make the calculations fairer? as it seems a shame when he's paid and paying so frequently to his two children overseas that this isn't taken into account with the calculations? Thanks in advance! 

WYSPECIAL

Trinidad and Tobago is a REMO country so it should be possible to get a court order which is enforceable in the UK