① First, create a new presentation and then go to the Review tab, and in the Compare option group, select Compare (combine another presentation with the current presentation);
② a "Select files to merge with the current Presentation" window appears;
③ again pops up in the window, select the PPT file you want to merge, and then click Open, and PowerPoint will insert the original presentation into the current presentation and select "Insert all slides in that location", and the original slide file will all be inserted into the current presentation.
④ of course, you can also open the original old presentation, the following figure, click "Accept", and then click "Accept changes."
⑤ "Accept the revision", wait a moment, the original presentation and new presentation can be perfectly merged, and the original presentation template, animation effects, etc. remain unchanged;
⑥ the presentation is better than the perfect merge, the new presentation will be inserted by default in front of the old presentation, first played, and adjusted to suit your situation.