Adding a common Container to Articles

We’ve used this excellent plugin since release to publish our posts on Apple News.

Just lately we’ve been playing around with Apple’s JSON format, adding a “container” to some example articles to produce a common footer for our Apple News channel.

We’d now like to add this new “container” to all the articles generated and published by Publish To Apple News.

From a quick look at the plugins stock functionality, i.e. Customize JSON and Themes, there doesn’t seem to be a way to add this container and the other accompanying elements it requires, (styles and layout).

Before I start to hack about, I was wondering if anyone had experience or a vague idea regarding the best way to add this custom element to articles produced by Publish To Apple News.