Q: Can I give zakat to my sister who is poor? Her husband earns only hand to mouth, but she has gold (her husband bought her at the time of marriage) which is is more than 85 grams (she is also saheb-e nisab), can I give her zakat or should I choose any other needy person?
A: You have written that she is Sahib Nisaab, so it will not be permissible to give her your Zakaat. If she has more than 85 grams of gold then she is certainly Sahib Nisaab and may not accept Zakaat.
Your Zakaat will not be discharged if you give it to her.
If your brother-in-law is not Sahib Nisaab and is legible for Zakaat, then you can give him your Zakaat.
Allah Ta’aala knows best.