Your sister is an a strict diet, but you are trying to persuade her to try one of your freshly baked cookies.

how will you make them say yes, and listen to you?

The best way to persuade your sister to eat the baked cookies would be to tell her that those are healthy cookies. The ingredients being used are for the ones who are on a strict diet. But you would be tricking her if this is the case. Hope this answers the question.