Is it permissible to give charity to an orphan girl in her twenties who is unemployed, when she has older working brothers?

The question about charity addresses two matters:

1. Charity in the sense of Zakat (obligatory alms): It is not permissible to give Zakat to a sister unless her brothers refrain from spending on her despite her need. The preponderant opinion in the Hanbali school of thought is that a sister's maintenance is obligatory upon her capable brothers if they are her heirs.

2. Voluntary charity (Sadaqah Nafilah): There is no harm in giving voluntary charity to a sister, knowing that orphanhood ends with puberty.