That's the whole point of Star Bread, and this graphic breaks down exactly how to think about fillings before you ever touch the dough.
The savory side: Pizza Star, Spanakopita, Buffalo Chicken, Ham & Gruyère. The sweet side: Cinnamon Sugar, Nutella & Banana, Apple Cinnamon. And the three rules that apply to every single one of them.
Moisture is the enemy. Keep your fillings spreadable. Divide everything into three equal portions. Follow those three rules and your star will hold its shape, bake clean, and look exactly like you meant to do it.
Pick your flavor in the comments. I want to know what you're baking.