Ensemble range (subset)

### What problem does your feature request solve?

Ensemble range for a subset of the ensemble members.

### Describe the solution you'd like

Recipe, may require some coding depending on which of the ensemble range issues are considered first.

### Describe alternatives you've considered

No file, test, or entry point is named. Start by reviewing the repository's existing recipe structure and the related ensemble range issues to determine how subset selection should work. Done should be defined as an agreed recipe for ensemble range over selected members, with the required implementation scope clarified.

Written by the indexing model from the issue text.