You can bind event from where you can (for example in child2’s BP) then copy that event node to child1’s BP. I know that’s a trick but it can do the work.
I’ve run into this issue as well, it seems like a big flaw in BPs. I currently have a sort of master blueprint which almost all objects of a given type inherit within my game, and if I need to bind events from one blueprint to another it is very difficult just because BP incorrectly always defaults to the current class’ event dispatchers.
The only workaround I have found so far is to redirect event dispatchers to their own subclass variants, ex.
(Base Class has Event Dispatcher) OnComplete
(Door Class extending Base Class) OnComplete calls new event dispatcher OnDoorComplete
(Button Class extending Base Class) OnComplete calls new event dispatcher OnButtonComplete
This seems very unnecessary and is essentially like reshuffling deck chairs, but right now it seems like the only way to actually be able to properly bind events between two classes inheriting event dispatchers from the same base.