So we just recently released a tablet only version of our magazine app. The project was set up as 1 top-level collection. Now we want to add in phone layouts (and submit an updated app), but I would love to not have to re-create a whole new project. Is there a way to change the current project to have phones automatically view a phone collection without doing the 2 top-level collections in a new project? Or, is there a way to switch the current project to 2 top-level? It's greyed out.
Does your phone version require different content than the tablet version? if so, then you'll need to create a new project with 2 top levels. But if your phone and tablet include the same content but you just want different browse page layouts, you can create layout renditions for phone and tablet.
If your content is responsive HTML, you'll likely be able to stick to one top level. If your content is InDesign-based fixed layout, you'll likely want to create a new project with two top levels.