We need to filter Portfolio Items (Features) based on the Releases that they are part of. We need to do this through the WSAPI.
The WSAPI call that can accomplish this is as below. Note the last part that filters Releases by Name.
https://rally1.rallydev.com/slm/webservice/v2.0/portfolioitem/feature?
workspace=https://rally1.rallydev.com/slm/webservice/v2.0/workspace/<WORKSPACE_OID>&
project=https://rally1.rallydev.com/slm/webservice/v2.0/project/<PROJECT_OID<&
query=(Release.Name contains "March")