How many generations can I immigrate at most now? Is it three or four generations?

As immigrants, they are all the first generation. The first generation of immigrants means that they were born in other countries and then developed in immigrant countries. The second generation immigrants generally refer to the children of the first generation immigrants in the immigrant countries. Their nationality of birth is not the country of origin of immigrants, but full citizens of immigrant countries. By the third and fourth generation, they can hardly speak their mother tongue.