Document Collection Members

Hi all,

I'm working with a client that is using a document collection in a workflow.
What they require is that once the document collection completes the workflow, it updates a field on its collection members.
I understand 'Collection Members' is a built in list field that isn't visible on the metadata card, but can it be used to indirectly get from the document collection to each of the collection members for example via a workflow state action? Or is there another option?