Quote Originally Posted by jdelano View Post
Maybe try using this command instead 
ActivePresentation.Slides.InsertFromFile FileName:="source.pptm", Index:=1, SlideStart:=2, SlideEnd:=4
Slides.InsertFromFile method (PowerPoint) | Microsoft Learn

thanks for the code, this looks like it’s just inserting slides rather than the masters, is that right? I am a newbie to vba, apologies if not