the proposed solution by @arama_mihai is on the right track.
It is possible to adjust the Velocity calculation to base it on sprints matching the name pattern.
If we had the member in the Sprint dimension as proposed by @arama_mihai (say, “Closed S1 sprints”, perhaps with the additional condition to filter closed sprints only) the formula for velocity would be:
-- filter last 5 closed S1 sprints starting from current sprint
Cache(ChildrenSet([Sprint].[Closed S1 sprints])),
Cache(ChildrenSet([Sprint].[Closed S1 sprints]))
-- only sprints with committed story points are retrieved
[Measures].[Sprint Story Points committed] > 0
[Measures].[Sprint Story Points completed]
Note also that this formula expects that you have added the “Closed S1 sprints” to the report rows and expand to the sprint level.
Janis, eazyBI support