Help me

[Ofnuts]

Basic technique:

• split the image into several sub-images, each on a layer
  
• enlarge the canvas with Image>Canvas size
  
• move the layers around to rebuild the image
  
• File>Export which will "flatten" the image.
  

Then there are plenty of ways to do the split. If you don't want to figure out how to install a a script:

• do a rectangle selection around each image,
  
• make a new layer from it: Ctrl-C, Ctrl-V, Ctrl-Shift-N
  

With my ofn-guillotine-layer script:

• add guides where you want the image to be split
  
• call the script to split the image
  

With my ofn-tiles script (if all images a regularly spaced)

• use the script to export the sub-images as individual files
  
• re-load the images with File>Open as layers