If a project is already created in PPM, how do we link the MSP (Microsoft Project) project to the existing PPM project?
While the MSP New Driver doesn't support the use of using Save As to overwrite an existing project like the MSP legacy driver does, the following document provides steps that may help to overwrite an existing project with a local saved MSP Project using the new driver.
Here's an option that has worked in some cases to workaround the behavior:
1. Export the existing project in PPM to MSP (This is needed to collect data from the project to put into the locally saved project)
2. In MSP, go to File->Options->Advanced and check the 'Show project summary task' box under 'Display options for this project' and click OK
3. Add the Text3 column to the view
4. Copy the content of the Text3 column for row 0 (Project Summary task)
5. Now, on the local copy of the mpp project that you are attempting to overwrite the PPM project with, do steps #2 and #3
6. Paste the content you copied on step #4 on the Text3 column for row 0 (Project Summary task) on this local copy of the project
7. Click Save on the CA PPM Integration tab to upload the project
If the above doesn't help, the other option would be to save the project back using the legacy driver, then switch back to the new driver going forward. It's recommended to test this out in a non production environment first to measure the impact since there are differences in behavior in the legacy versus new driver.