The development team confirmed that you can only start ONE of the product releases at a TIME on an LPAR in the RIMPARM member. When a site tests the r 10 products(Intertest CICS and Batch, Symdump CICS and Batch ) you CANNOT test on an LPAR where CA Intertest batch and CA Symdump batch r 9.1 have been initialized under CAIRIM. Only one runtime is allowed to be started on the LPAR and the corresponding load library must be added to the linklist.
Also, as per the Install Guide(See the Links below) an IPL is required when you are changing releases. Since the CAIRIM step loads modules into system storage an IPL is the only way to refresh the modules.