Currently we have the option turn on "Save Shared Pages Belonging to Anyone" across all projects, which will allow anyone who can see the page to edit it. Otherwise, only the owner can edit the page, it would be better to have more granular permissions.
For example, it would be very useful to have edit permission limited to several users.
This also benefits the case when the page creator leaves the company. Currently we can't transfer the page ownership to another person. To make the page "editable" again we have to copy the page as a new page... not ideal since artist already have bookmarked the original page.