@Mohamad - You can almost always use any previous MP, and it will be "supported" as long as the MP is currently supported. SCOM 2012 R2 is fully backwards compatible with previous MP's. We wont always update the documentation to call out support specifically for new versions of SCOM for the older MP's. We will drop support for a management pack at the same time the product itself falls out of mainstream support. Understand, "support" for a management pack generally means having an escalation path to request fixes to any issues found in the field, or specific to environments.