I need to be able to guarantee that a certain function is called every frame before any other blueprint tick functions are called. Is there any guarantee that, say, the level blueprint’s tick function will always be called first? I need to know where to call my function. Thanks!
The GameInstance is one of the First Gameplay objects thats get added to the Ticker Array. However, that will be at the start of the game launch and not the level.
Yes you can do “Get Game Instance”, you can also extend the Game Instance with your own Blueprint. the Ticker Array is on the c++. The tick functions the level and actor use is actually different and put into TaskGraphs. These task graphs can be ran differently depending on multi-threading… ect. There are maybe some inconsistencies of what ticks get ran first. This is all at a high level and my brief knowledge of the TaskGraphs. Maybe someone more knowledgable can confirm or correct 
Is there a way for me to edit the GameInstance blueprint? I’m mainly asking about easily editable blueprints from within the editor. I’m not too privy to diving into engine source code.
Also I can’t find any information on the ticker array you’re talking about, are you sure that’s what its called?