Funny his ultrasound was not free, all our pre natal and follow up tests and treatment was free, why does he have to pay, he is Dominican right, only pay for actual medicine or voluntary treatments, ultra sound is not a voluntary treatment, it is part of pre natal care, free!!
The only person responsible for your adoptive brothers bothering you for money is you. Somehow you have lined yourself into this position. It is common among visitors, or people down the tourist areas as they like the feeling of authority through thickness of the wallet, admit it or not, 99.9% of this is self inflicted.
The top and bottom of it is if you look or act like you are either daft enough to give money away, or money is not a factor in you life, or you will give up to intimidation you are a mark, you will continue to be hassled. It is true there is no getting away from it on the North until your face is known and accepted as a permanant fixture.
I found that if you are firm and very direct with Domincans they will not like it at first, but they will respect you for it, and eventually you will be accepted to some level, maybe even an equal, and they never ask each other for money, they won't lower themselves to each other.