Using Mari for texturing (multi-patch texturing)

I’ve created a pretty complex model and I’d like to paint it in Mari. However, Mari’s main function relies on multiple UV patches which doesn’t seem to work properly with UE4. Mari wants UV sets separated into UV tiles 0-1, 1-2, 2-3, etc but UE seems to complain when there is more than just the default 0-1 texture space.

It’s clear that some Epic content uses complex texturing (notably the knight in Elemental demo) but it’s all slapped on top of itself in the 0-1 space. If I were to do that, Mari (nor Mudbox) wouldn’t be usable as a painting system since the paint would apply to all the UVs that are stacked on top of one another. What is the proper workflow here? I’ve searched EVERYWHERE and haven’t found any mention of this anywhere.