Alimony Demand From Brothers Wife

How to safeguard my parents and my family (I, Son and Wife) from younger brother's in law's false charges that I am guiding him for dowry and using his earned money for my family. we are muslims. For marriage, the girl's family reached us through matrimony website and committed to offer my brother a house on his name and gold jewels however they have recently sold that house which was on her father's name and hidden the gold jewels and also demanding monthly maintenance of 20K for his wife/kid who left him in a month time and delivered a baby boy without involving him. My bro's wife has stopped every communication with him past 2 years however her dad is only emailing him with his demands. Since he has not been in touch with them and not providing any maintenance to his family, their in laws are demanding money related settlement from me - is this legible/am I or parents legally bound here. how to handle them. my parents are old and are dependent on me financially (not earning and no property of their own). will moving to new city and changing my contact details help. Kindly assist.