Not sure about what "2. Added check like for certain cases only Routing step should have reporting step" means.
All routing steps that come from ERP must have Reporting Step.
If you need to have only one ERP Reporting Step, you can import LOIPRO with a one-step routing without auto-release of the order, then update the routing in Routing Maintenance of SAP ME to add whatever steps you need before and after this ERP routing step, and then release the order. Then all component assembled before the reporting step will be confirmed to ERP when you complete this step.
As alternative, you can update the ERP routing via XLST of SAPMEINT to include non-ERP (ME-specific) steps.