Populating a PageReference multi-select field via the API

[cjx2240]

How might I populate a page reference multi-select field (with options limited to pages of a specific parent) using the API? I'm doing some manual data importing and I have some categories in json like this (which came from the first-party Export/Import module)

"categories": [
                    "/categories/dance/",
                    "/categories/film/",
                    "/categories/poetry/"
                ],

The pages are all set up correctly on the source site, with the same names

I've done images, repeaters etc, but I'm not clear on the syntax for populating a pagereference field. Something like

$page->categories->add($category);

(Where category is that path from the loop) Is what I was hoping for

[cjx2240]

As is so often the case from the magic of rubber duck programming, I realised that $category needs to be the page I've made. While ProcessPageExportImport probably does something clever with those paths, in my case I needed

$page->categories->add($pages->get("path=$category"));