Your sister-in-law has burned that bridge. She cannot be trusted. You should speak to her and let her know how selfish and deceitful her behavior was regarding her maternity leave and returning to work. While people do those things sometimes in order to get as much money out of their jobs as possible, she is family. She should not have taken advantage of you in that way. Unless she is your only option, don't hire her back.
At first, I was overthinking it. But it's actually pretty simple. You just use the Web Object feature, paste in the embed code (like from YouTube or Vimeo), and it fits right into your slide.
Performance reviews aren't well liked by many managers or employees. Many managers feel like it's just another box to check and employees feel like they make no real impact in their career growth. At some companies, performance reviews primarily exist mostly as a punitive tool for underperforming employees. I'm an advocate for performance reviews (when done well) and think that they shouldn't be a dreaded task once a year, but instead part of an ongoing conversation.