Let's say you are a naturalized U.S. citizen and have an unmarried teenage daughter who still lives in our native country and has given birth to a child. If you sponsor your daughter for a U.S. green card, can she bring her young daughter to the United States as well?
Unfortunately, the answer is "no," as discussed in this article. But read to the end for alternative strategies.
The issue arises from a technical (and often illogical) aspect of immigration law, having to do with which immigrating relatives can bring their own "derivatives" (spouse and minor children) to the United States on the same application.
In cases of immediate relative relationships (the spouse, parents, and unmarried, minor children of U.S. citizens), derivatives are never allowed. U.S. citizens must be able to directly file a visa petition (Form I-130) for every person that they wish to help immigrate. In order to do that, however, a citizen's relationship with the "beneficiary" of the petition must be recognized as a qualifying one under U.S. immigration law. The law simply does not recognize grandchildren of U.S. citizens as having a qualifying relationship for I-130 filing and green-card eligibility purposes.
As we mentioned above, there are strategies that might help a U.S. citizen's daughter avoid separation from her own child, though it means her path to a green card will take longer.
The first is for the daughter to wait until she is 21 or over to immigrate. In that case she will not be an "immediate relative," but instead be classified in the "family first preference" (F1) visa category. Preference relatives are legally allowed to bring their derivatives (spouse and unmarried minor children) with them to the United States. The down side to this strategy is that there is an annual limit on F1 visas, as a result of which a waiting list has developed, and it could take several years after you file the I-130 for your daughter to be able to move forward with a green card application. You'd need a lawyer's help to work out the details of timing this correctly.
Another, similar possibility is to wait until your daughter gets married, in which case she would be classified under the "family third preference" (F3) visa category. Because this, too, is not an "immediate relative" category, she would be able to bring her spouse and child. But the waiting list in this category tends to be even longer than in F1.
These are complex issues and suggested strategies, so again, your best bet would truly be to consult with an immigration attorney for a full analysis and for help in properly preparing and filing the paperwork, as well as working out how best to time the whole process.