Is it permissible to give the full amount of Zakat, estimated at one hundred Jordanian Dinars, to a married sister who is experiencing financial hardship, or is it better to divide it among more than one sister?

The poor person eligible for zakat is one who does not find enough to meet their essential needs, along with those whose sustenance is their responsibility. If your sister is in such a situation, then it is permissible to give her zakat. In fact, she is more deserving of it, for the Prophet, peace and blessings be upon him, said: "Charity given to a poor person is charity, but charity given to a relative is two: charity and maintaining kinship ties." Any sister who fits the description of poverty is eligible for zakat, and it is better to give it to the one most in need among them.