Unfortunately, ServiceStack.OrmLite does not support multiple result sets unless combined with Dapper. ServiceStack MARS (Multiple Active Result Sets) using ORMLite and Output Parameters
Alternatively, you can use the .Net SqlCommand. Return multiple recordsets from stored proc in C#
ServiceStack.OrmLite V4 notes: https://github.com/ServiceStack/ServiceStack.OrmLite
ServiceStack.OrmLite V3 notes: https://github.com/ServiceStack/ServiceStack.OrmLite/tree/v3