You are mixing requirements and design (more specifically, use cases). Requirements describe the high-level functionality that the system should be able to provide.
Use cases are derivatives of the requirements.
So your requirements can be:
1. For scenarioA do this
2. For scenarioB do that
Note, the requirements are context-free and essentially describe capabilities.
And from these requirements a use case (or even several) describing a certain dynamic behavior can be defined:
a. Step 1
b. Step 2
...
n. [ScenarioA] do this
n1. [ScenarioB] do that (alternate path)
...
Here, the n
and n1
steps are defined in scope of the use case context and have not meaning otherwise.