If you use the framerate override in source settings it will play at the project frame rate so footage will slow down or speed up depending on what the fps was before.
This is ok for say 24 to 25 fps or 23.98 to 25 fps but little use for 29.97 to 25fps.
The standard way of doing it was to AMA link the sources in a project setup to match the source frame rate.
Then transcode that footage and copy those bins to the working project. MC will now add motion adapters to allow the sources to play at the project frame rate.
Come the conform you can tweak those motion adapters or promote to fluid motion or externally have them framerate converted and re-cut in.
Pat Horridge
Broadcast & Post Consultant, Trainer, Avid Certified Instructor
Free online Tutorials at VET digital media academy online https://vimeo.com/channels/752951
pat@vet.co.uk