I would like to be able to have an Epic ticket associated with a top level item (Initiative), without having a second tier container ticket (Milestone) in the middle.
Using advanced roadmaps, we've configured a multi-level hierarchy to allow for epics to be contained in milestones, and milestones to be contained in epics.

The roadmap settings interface shown above allows me to associate multiple ticket types with each level in the hierarchy, but a given ticket type can only be associated with a single level. So with Epics as level 3, they are not available to select as level 2. And with Milestones as level 2, they aren't available at level 1.
I've also tested having one type at level 1 (type A) and two ticket types at level 2 (B & C). In that scenario, a level 2 type of ticket (B or C) can have a parent link of ticket type A (level 1), but not of either type B or C (level 2).