I'm going to call my sister out on her massive dumps
What can you sister do about her dumps?
I want her to stop. It smells horrible. I already asked once, but I think she doesn't hear me because of the massive volume
Approach your sister in a calm and rational way and try to address the situation in a respectful manner. You'll avoid embarrassment for you both and get to the root of the problem much quicker.
That is impossible. If I do that, she wouldn't do it. I'm going to put a face mask on and deal with it.
Maybe your sister can't help her dumps. You shoudl suggest she talk to a doctor.