ANSWER:

This udhiya is sufficient for your father and all those living under his roof regardless whether they are earning or not. Your brother who lives abroad has to offer his own on behalf of himself and his family. 

QUESTION: Sheikh my father does udhiyah every year اَلْحَمْدُ لِلَّٰهِ and that is one lamb for the family of 4 who lives under him; including himself ( my brother lives abroad with his wife and two kids and he sometimes either share the money or do it completely. I have been earning for 1.5 year and i saved money from comity to do it this year. Sheikh i wanted to know if i can pay for it under my mother’s name