ANSWER:

This is absolute nonsense and a superstitious belief that has got nothing to do with Islam! Such belief can mount to shirk.

My sister in law to be had passed away some months due to dengue after I got engaged. A couple of months after I got married my mother in law passed away due to covid. Now my sister’s in law think I am unlucky for their family. Is there anything in Islam in agreement with this theory where a person brings death or bad luck in the family after coming into it?