@denisepowell - Movicol is a new product to me so I did a brief web hunt. https://www.movicol.com.au/about-movicol/how-it-works/
Am I right in guessing that Macrogol, its active ingredient is similar to Miralax, but perhaps sold in Australia? Movicol added electrolytes, maybe to reduce its sodium/potassium/other? mineral losses. My source was Wikipedia:
https://en.wikipedia.org/wiki/Macrogol
Have you found it helpful? Is Movicol sold in the U.S?