New York: Nabila Khan would not be in the United States if it were not for her sister. It was that sister who sponsored Khan's immigration from Pakistan.

Four years ago, Khan started the process to do the same for another sister, the only one left in their native land.

They are family, she says, and have a bond that has not lessened despite the distance between them and the years they have been separated.

But a proposed reform to the American immigration system could do for many citizens and their relatives what time and distance have not been able to do.

An agreement announced on Thursday by a bipartisan group of senators and supported by the White House would put severe restrictions on the family members immigrants can sponsor for visas - a proposal critics call a slap in the face to cultures where family trees have many more branches than in the US. In cultures around the world, aunts and uncles are surrogate parents, cousins are as close as siblings, and blood ties stay strong through multiple generations.

Supporters of the change laud it as a way for the United States to get control over an unwieldy, backlogged immigration system, and say that part of becoming an American is adapting to American cultural norms like the nuclear family. "In our immigration policy, we have to look out for the well-being of America and Americans first," said Caroline Espinosa, spokeswoman for NumbersUSA, an organisation that supports immigration restrictions.