Is it permissible to give money and gold to one's sister's daughters, whether during the giver's lifetime or after her death, given their good relationship with her and their distinction from other relatives?

A person has the freedom to dispose of their wealth during their lifetime through gifts (hibah) or charity (sadaqah) to whomever they wish, provided that they do not intend thereby to disinherit the heirs or cause them harm after death. Such an intention is forbidden and is considered a contradiction to Allah's wisdom in the division of inheritances. As for after death, a will (wasiyyah) is permissible within the limits of one-third (of the estate) for a non-heir, provided that the intention is not to harm the heirs. Causing harm through a will is considered one of the major sins. A Muslim should fear Allah and not strive to deprive heirs of what Allah has obligated for them.