oficial/app/resources/routes/ventas/pies.php

<?php
use Incoviba\Controller\Ventas\Pies;
use Incoviba\Controller\Ventas\Cuotas;

$app->group('/pie/{pie_id}', function($app) {
    $app->group('/cuotas', function($app) {
        $app->group('/add', function($app) {
            $app->get('[/]', [Cuotas::class, 'add']);
            $app->post('[/]', [Cuotas::class, 'doAdd']);
        });
        $app->get('[/]', [Pies::class, 'cuotas']);
    });
    $files = new FilesystemIterator(implode(DIRECTORY_SEPARATOR, [__DIR__, 'pies']));
    foreach ($files as $file) {
        if ($file->isDir()) {
            continue;
        }
        include_once $file->getRealPath();
    }
});