Multiple menus for Fortuna theme

Hi!
I’m using fortuna theme for one of my clients who is asking me to set the homepage as a one-page site, with a main menu using anchors, but with links inside the page sending users to other pages containing an other main menu with sub-menus this time … As this is a client request, I have to find a solution to resolve this problem. So far, I’ve seen in the appearance/menu section of the theme that fortuna does not support multiple menu. On the other hand, I’ve seen in your demo pages that you have a single page template with a main menu without sub-menus, and inside this one-page template, when you click on a portfolio item for example, you’re linked to a portfolio page which has another main menu with sub-items. So, I do not know how you do this, but this is what I’m looking for : a single landing page set as homepage with a main menu in the header directing to anchors, and links in the sections of the homepage leading to other more detailed pages but with a more detailed menu in the header, with sub-menus.
I’ve seen in an old post that you do recommend a plugin to do this (CE WP menu per page), but the mentioned plugin has not been updated since 2 years and the plugin page doesn’t say anything about compatibility with latest wordpress version …

Could you explain me if there is some hope there with my issue and if by any chance I could set multiple menus somehow?
Thanks a lot for your support and your great theme (which needs multiple menus built-in by the way …;))