According to the docs document.guides is a read-only property, so you can’t assign something to it. Unless someone here knows a better solution I would iterate through the guides property (the docs says it’s an indexable structure, so I’d think you can loop through it) and re-create them one by one (with coordinate and direction of the original) in the other doc.
I figured out how to read orientation and coordinates for each guide.
Then new guides can be created based on those. It’s a little more work to do but not too bad to just loop through them all. I’ll post the finished code when it’s working.