I express a deep gratitude to the staff of the center, and personally to Elizabeth Krukova and Sofia Ladygina for the support and assistance in my case! In short, the situation was as follows:
While being in the process for a green card, I didn’t apply for my wife and child; therefore, I had to do the process of family reunion later. All the lawyers, who I have consulted with said that the reunion is almost impossible, until I obtain a citizenship, and calculated the amounts from 10 to 20 thousand dollars for the initial work on cases.

Only at National Capital Legal Services, during the first consultation with Elizabeth Krukova, I learned that for a very reasonable price and terms my family can be reunited and the problem can be solved. It took less than 2 years from the filing of the case with the immigration services to the receipt of the green cards by my family.
Therefore, I strongly recommend contacting the National Capital Legal Services in case of any issues.