Bespoke plugin for importing content to multiple sites

I'm looking for some help in how to go about creating a plugin.

The situation is - I have a network of WP sites that a publish content to.

The content is CTPs so I can't use my normal management tool (ManageWP) to publish it to the network.

Instead, I export an XML from a master site (using import/export plugin) and then add it to each site in the network individually.

Was would be better is if I could export the XML once, add it to a plugin and then publish the plugin to all the sites in the network (which I can do through ManageWP).

What'd I like is when the plugin is updated, it bring in the new content just like the import/export tool.

Any ideas on how I could achieve this would be great.