Beware of this HSMP problem (Dependents)

Hi........again your help needed
Facts………..
I am in UK under HSMP scheme and I already have four (4) year extension on my passport.......
My wife and son have initial 1-year dependent visa, which will expire in next week and they come to UK last week………………..

Explanation………

When I got my 1st year HSMP approval for myself and my wife and son.... they remain in my country because my wife was pregnant and not able to travel.......when she had new baby we applied for new baby visa but embassy rejects the visa.......we applied again together for my wife and son and new born baby as I already got 4 year extension but they reject the visa again.....

my wife and son (they still have visa) moved to UK while newborn baby remain in my country with my mom...now they are in UK and we want to apply for them ASAP...so that my wife can go back and we sort for the baby visa...

I contacted relevant authorities and they assure me that I can apply for their extension via FLR(O) form
But I got 2 answer from same office (public enquiry office) one suggest that I should apply in person and pay 500 for both other one suggested that i should apply for them separately via post because this case is complicated case and cannot be decided immediately
I am renting house pus working in my profession and I have around 4000 pounds in my account ...any suggestion................

many thanks