matgate said:My mom is living with one of my brother and she got a whole family there (my maternal family). My younger brothers are there in Canada and they are stable financially, is there is an option for them to become a petitioner in place of my mom?
No, there is no way. Your sister does not qualify under any family class sponsorship. She could only be sponsored by a Canadian spouse and that's it.
Or she would need to immigrate independently via skilled trade or something.