What are the conditions for Parent Relief Tax?

This is my first year as a working adult, and I am wondering about parent tax relief. My parents are both about 65, and I read that I can have a tax relief of up to $9000 per dependent, provided all conditions are met. May I ask, does the tax relief go up to how much i spend on my parents or is it flat out 9k x 2? If my brother is also supporting them, do we share the relief?