While transitioning to SAP GRC 10, you may need to have SAP GRC 5.3 also in the same system. However, when you install the GRC 10 plug-in, you may experience some issues using the 5.3 version.
SAP has a recommendation on the same in SAP note 159030.
The note provides detailed steps that one should take before upgrading to SAP GRC Access Control 10.
Additionally, you may also refer:
SAP Note 992200 - for implementing SPM 5.3 User Exit.
SAP Note 1545511 - for implementing AC10.0 SPM User Exit.
SAP Note 1573023 – Master Note for SAP Access Control 10.0 – Support Pack 4
SAP Note 1352498 – Support Pack Numbering – GRC Access Control