The USCIS prefers not to separate families. Chargeability allows a spouse or child of a preference immigrant to “accompany” or “follow to join” the principal beneficiary of an immigration visa – by charging their priority date to the country of the principal beneficiary. If the spouse or children can’t adjust their status independent of their relationship with the principal immigrant, the spouse/child “derives” their status from the principal immigrant.
The terms “accompany” and “follow to join” are different. The Department of State “generally considers the derivative spouse or child to be “accompanying” the principal when issued an immigrant visa or adjusting status within six months of the date DOS issues a visa to the principal or the date the principal adjusts status in the United States.”
“ In contrast, there is no specific time period during which a derivative must follow to join the principal.”