How to Steal Slides from Another PowerPoint 2013 Presentation
Open the presentation you want to copy slides into.
Do not open the one you want to steal the slides from yet.
Click the Home tab on the Ribbon and then click the New Slide button and choose Reuse Slides.
Reuse Slides appears at the bottom of the New Slide menu. This step displays a Reuse Slides task pane, which appears on the right side of the screen.
Click the Open a PowerPoint File link in the Reuse Slides task pane.
This summons a Browse dialog box.
Locate the presentation you want to steal slides from and then click Open.
The slides from the presentation you selected are displayed in the Reuse Slides task pane.
You’re now privy to one of the coolest effects in PowerPoint: When you point at one of the slides in the Reuse Slides task pane, the slide magnifies to twice its original size so you can better see the contents of the slide.
(Optional) Select the Keep Source Formatting check box if you want the slides to retain their original formatting.
Normally, you should keep this option deselected. With the option deselected, the slide assumes the theme of the presentation it is inserted into.
Click the slides you want to steal.
Each slide you click is added to the presentation.
When you’re done, click the X at the top right of the Reuse Slides task pane to dismiss it.