Extending Mockup Pattern Functionality (pickadate)

I'm looking for some solutions as to the best way to re-implement or extend the functionality of a mockup pattern, in this case, the eventedit pattern which uses the pickadate functionality...

In the plug-in the following is defined:

jq_start = self.aOrB(
        $('#formfield-form-widgets-IEventBasic-start', $el),
        $('#archetypes-fieldname-startDate', $el)
      jq_start.each(function () {
        $(this).on('change', '.picker__input', function () { self.updateEndDate(); });
      jq_end.each(function () {
        $(this).on('change', '.picker__input', function () { self.validateEndDate(); });

You can see the complete class and its code on GitHub.

By modifying or updating an input using the pickadate pattern, a corresponding input with the #formfield-form-widgets-IEventBasic-end ID is updated automatically to match the start date selected.

This functionality is specific to the eventedit pattern, but I want to extend the "jq_start" and "jq_end" objects to implement other ID names, not just #formfield-form-widgets-IEventBasic-xxx specifically...

This is in the pursuit of clean code, but what would be the best way of doing this..? Copying the pattern, re-compiling, inheriting..? I'm not entirely sure what the best approach.

Just to note, that assigning the start and end elements with the ID names defined in "jq_start" and "jq_end" does in fact give the desired effect, and it works, although I'd prefer not to use such an explicit ID since the context of the form is not an Event item.

Thanks for any help!