Can I make sure observe callback in order?

Any way to get called observer fuction in order?

I have ObserverFoo class.

and both ChildObserverA and ChildObserverB inherited ObserverFoo.

the problem is the observer callback should be called from ChildObserverA first.

Because there's dependency between ChildObserverA and ChildObserverB.

is it any good pattern to make sure ChildObserverA::Observe() called first?