WordPress plugin to extend theme with jQuery tool

Overview: Integrate the Zurb TwentyTwenty jQuery plugin into the WordPress theme 'Inviticus' to extend the options for the individual Photo post (CPT) for a before/after interface within a slider, similar to the Multipurpose Before After Slider WordPress plugin. [login to view URL] [login to view URL] [login to view URL] Functional requirements: 1. PRIMARY REQUIREMENT Option to select 'Before/After Slider’ for the ‘Image Settings’ on the Photo post edit admin screen. This allows pairs of images to be selected using the WordPress Media Uploader to display a slider with the TwentyTwenty plugin allowing a before and after on each slide on the single post page. When there is only one pair of images defined, there should be no navigation dots. (See Fig. 1,2,3, and 4). 2. Option to select 'Before/After' for the ‘Project Settings’ Link Type on the Photo post edit admin screen, with two fields to select a before image and after image using the WordPress Media Uploader. This would display the TwentyTwenty plugin when the image appears in the portfolio (gallery) templates. (See Fig. 1, 5, and 6). (no slider required here) Portfolio templates this would apply to: Portfolio 1 Column Portfolio 2 Columns Portfolio 3 Columns Portfolio 4 Columns Portfolio Fullsize Scroller Portfolio Masonry Portfolio Sortable Grid 3. Be able to update theme without the custom code to be lost. My thought here is to house the input changes to the edit post page in a plugin, then use a child theme to manage the template changes, but if there is a way to inject the template code into the parent templates without a child theme, then that would be preferred. See attached files for reference