I am working on a project that has three testing teams. Each of these teams should write and run their test scripts from one set of requirement document. I want to be able to create a matrix to map a test script to a particular requirement.
regardless of how many test teams are to test you need to track the requirements to functional specifications and to test case.
Ask each team submit to you their test cases along with requirement item which the test case is mapped to.
Combine them all and create your RTM.