Hi Bill,
At the moment the plugin is limited to two custom dropdowns. However I do custom jobs for our premium members (https://geek.hellyer.kiwi/premium_support/) with whatever combinations of HTML and codes needed to get your dropdown working.
Remember that you can have multiple top level menu items from one custom code option. The only time you would need more than two custom code options would be if you wanted custom codes seperated by multiple automated dropdowns such as ‘Pages dropdown’, Categories’ etc. – hopefully that made sense!