Sorry for the lack of updates regarding this one.
While linking to alternates is something we are talking about, we did recently introduce the ability to group mockups together, allowing you to have "official" versions of your alternates without filling up your project navigator, more details here.
This allows you to create different versions of a single mockup, hide them by closing the tree as needed and, last but not least, link to any of these mockups. See the example below:
Hope this will work for you all. We're here to help if you need anything else!