Naming multiple swashes for same letter

I have six different swashes for the letter s. How should I name them so that they appear in the swsh feature?
The first is named s.swsh and it shows up in the feature.
Thanks

That is not possible. The swash feature can only substitute one normal shape with a swash form. You might have a look at this: https://www.glyphsapp.com/tutorials/features-part-3-advanced-contextual-alternates