The TMMi process areas complement the CMMI process areas for Verification and Validation by providing more detailed guidance specific to testing. While CMMI defines these areas at a high level, TMMi elaborates on how to establish and maintain a defined testing process that includes both verification and validation activities. The relationship between the two models is complementary rather than hierarchical, meaning that improving testing processes using TMMi can lead to fulfilling CMMI requirements for Verification and Validation.
Reference:
"The TMMi process areas provide support and a more detailed specification, especially of what is required to establish a defined verification and validation process".