It would be pretty rare. But an attorney could try to petition the court for early or temporary release based on the family circumstances. Again though, it would be pretty rare that a federal court would allow for something like this.
The better the reason, the more harsh the lesson for inmates, don't do the crime because you are going to miss out on some very important stuff on the outside. I have heard Judges say these type of things all the time. In the Federal courts I am sure it is the same.
The federal courts no longer have any jurisdiction over your brother and the sentence he is serving. He is in the custody of the Bureau of Prisons, and your only remedy lies with them. There may be a federal statute that authorizes the BOP to grant an early release or a furlough of some kind, but I'm not certain at all. But you have no recourse in the courts at this point.