Custom changes to WooCommerce Subscriptions plugin

We're currently using the WooCommerce Subscriptions ([login to view URL]) plugin but want to make some changes to it in order to add extra functionality. This project is NOT currently on the plugin development roadmap and after consultation with the plugin developers, we have decided to custom code this addition rather than wait for it to be added to core functionality. Currently Woo Subscriptions allows a customer to suspend their account. They log in via the front end and can click on a "Suspend" button to suspend their account. See [login to view URL] We want to add extra functionality to that process as follows: 1. Customer clicks on the "Suspend" button. They either receive a pop-up / pop-over (this is our preference) or are taken to a new screen. 2. Customer sees the following: How long would you like to suspend your account? [radio button] [text box] weeks [radio button] Indefinitely. I'll manually re-start my subscription [submit button] This gives the customer the ability to decide how long they want to suspend their subscription for. They can either enter the number of weeks that they want to suspend their subscription (so... for example, 2 weeks), or they can suspend their subscription indefinitely and manually - which is what currently happens when they click the "Suspend" button on their "My Account" screen. If they elect to suspend their account for a set period of time, our extension to the plugin needs to make sure that it automatically re-enables their account after that time has expired. From speaking with the plugin developers: The action scheduler can be used to to do this. On keypress, you could hook into the suspension (there are hooks that fire when subsciptions' status turns to on-hold, and then you can schedule an action into action scheduler, and then when that fires, use another snippet of code to reactivate the subscription.) In that respect, this shouldn't be too difficult to accomplish. The plugin is well documented. We DO need to make sure that when we update the core WooCommerce Subscriptions plugin, we do not lose these custom changes.