CREATE NEW PLUGIN TO EXTEND FUNCTIONALITY OF "PREMISE" PLUGIN

ABOUT THE PREMISE PLUGIN Premise is a membership plugin from [login to view URL] It creates a paywall, landing pages and secures content within Wordpress. THE PROBLEM WE WANT TO FIX When the plugin locks content, the post page only displays three items: 1) The Post Title 2) Post Metadata (e.g. author, time date) 3) Standard login message “Please Log in to view this content.” SEE IMAGE: EXISTING PAYWALL WITH MESSAGE We would like the plugin to display: 1. The Post Title 2. Post Metadata (e.g. author, time date) 3. The Excerpt (when available) 4. A new login interface and option to buy a membership as shown in the "Sample New Interface" illustration below. SEE IMAGE: SAMPLE NEW INTERFACE This additional post information is currently generated by using an unlocked post, and then manually adding HTML and Premise shortcodes to lock parts of the post page. This is time consuming and we want this to be automatic. We would prefer this information to display by default when a page is locked, so that we don’t need to manually generate this code each time. PREMISE ADD-IN PLUGIN We would like to activate these changes, using a customisable plugin. The plugin should extend the existing functionality if possible, rather than changing existing premise code. if the plugin is deactivated then the standard plugin code should work as intended The plugin should be called: PREMISE PAYWALL ADDON Images should be stored locally, as defined by the plugin when installed. If a user goes to the backend, they should be able to manually change the images. We will supply all images in transparent PNG format. 
We will supply the code for Premise plugin so that you can install and use for testing