We have got an immigrant visa to USA for me and family and we will travel next month.?

I have a problem that I can not stay at the USA tfor a long time because my father is living alone in Egypt and my mother died so I cannt immigrate and leave him alone. Some people told me to submit for a white passport by submitting medical certificate of my father showing that he cannt live alone and I should support him and so I can stay with him for two years without travelling to USA. I want to know if this will be applied for me only or for my kids and husband? or can they travel the next year alone or we should be all together as we received our immigrant visa together? and if i applied for the white passport and the problem is solved can I go next year or I cannt travel except after 2 years? Will these two years affect the citizentship period to be 7 years instead of 5 years. Will these procedures applied for me and my family members too or me only as he is my father or the white passport for all my family? and what is the best to do? Pls help Tks.