Is it permissible for a brother to give Zakat to his needy, working brother whose income is insufficient, and to his poor paternal uncle? And can a woman give Zakat from her money to her brother, paternal aunt, or sister?

There is no harm in giving zakat (definition) to brothers, sisters, paternal uncles, paternal aunts, and other poor relatives. It is both charity and a act of maintaining kinship ties, for the Prophet, peace and blessings be upon him, said: "Charity given to the needy is charity, and charity given to a relative is both charity and an act of maintaining kinship ties." Exceptions to this are one's parents and children; zakat should not be given to them. Instead, one is obligated to spend on them if able.