Dispatch multiple, ordered, actions from effect in NGRX

Question

I'm using the Splitter decider pattern to split out a single action into two actions:

Class TodosEffects{

Constructor(private actions: actions) {}

@Effect()
public todo$: Observable<Action> = this.actions.pipe(
   ofType(‘REQUEST_ADD_TODO’),
   map(action => action.payload),
   flatMap(thing => [
         {type: ‘ADD_TODO’, payload: thing},
         {type: ‘LOG_OPERATION’, payload: thing}
   ]);
}

I've taken the code of the Splitter decider pattern and updated it to ngrx 6.

This is pretty close to what I want, but how can I maintain order? With this example, I'd like the ADD_TODO action to complete, then, call LOG_OPERATION.

As it is, both actions are dispatched without much control. I like the idea of combining actions in a single Effect() for code re-use, but without the ability to maintain order this approach is not much help.