回复：Help sister immigrant to

Option1: Apply as an independent immigrant herself. She can add some point to herself because you are a PR in Canada.
Option2: Apply for your parents and add your sis as your parents' dependent ( Family ). You have to make sure she has NEVER been worked. She needs all the support documents for herself to proof that she is always being school, never made money to support herself.

If she is asked for an interview, that will take about 18 months. If luckily not, will be as fast as your parents.