If you are a family immigrant from the United States, do the new immigrants have to go through customs together for the first time?

For family immigrants, they need to be notified before entering the United States.

Inseparable.

After the whole family enters the country, the follow-up work of the Immigration Bureau can continue. You didn't finish your work when you entered the country. There are many things, such as sending letters to your home, changing green cards, work permits and social security codes.